Contours--The CORE GIS Blog

Six Seasons of CORE GIS Holiday Cards

2011-12-22T14:43:00.000-08:00

Each holiday season for the past six winters we've produced a custom card to send to colleagues and clients. I thought it might be fun to post each of the designs, especially for more recent acquaintances who may not have seen the earlier editions.

Happy Holidays, everyone!

2006: Happy Watersheds

2007: Christmas Island

2008: Holiday Topo Map

2009: Map Sledding

2010: Global Seaturtle

2011: Holiday Compass Rose

Teaching Geography to 2nd Graders

2011-12-15T15:22:00.000-08:00

My son is in second grade, and his teacher was absent for a couple of days this week so I volunteered to teach the geography lesson. I spent about 45 minutes teaching the kids about geographic projections. It was so much fun! The kids were all enthusiastic, attentive, observant, and lots of fun.

We started with a discussion about the shape of the Earth, using a globe as an example, and talked about why it's usually more convenient to have a flat map on paper or on a screen when you need to do something map related. Then we talked about how the transition is made from three dimensions to two, and I passed out a satsuma to every student. I asked them to pretend their orange was the Earth and asked them to transform the orange peel into a flat, rectangular surface. Before they began, I explained that there is no wrong or right solution, and that the task is in fact impossible--but it would be really interesting and fun to try to solve it. They worked cooperatively to complete their 'projections.' After all the kids were finished, they ate the oranges, then took turns table by table looking at the solutions generated by their classmates. I asked them to make observations: what did the solutions have in common? how were they different? what conclusions could they draw? Then we gathered on the floor and they shared their observations.

This is the part that really blew me away--of course, they all quickly ascertained that it was a very tricky problem, but they also understood that for small areas, it was possible to minimize the distortion of the peel, and that certain patterns seemed easier to work with than others. Many of the kids kept their peels in one piece, some intentionally split them into numerous pieces and re-assembled it, and some did a bit of both. During the discussion, every student made an observation or asked a question, and many did both.

After the discussion I drew a picture illustrating the mechanics of translating the a sphere to a flat surface, then showed them a poster I prepared showing nine different global projections, ranging from Mercator to Sinusoidal to Goode-Homolosine. We didn't spend a ton of time on any particular projection, but we did discuss the various applications for some of them (i.e., Mercator is great for navigation but not so good for wall maps) and they all saw that the projections are just as varied as their orange-peel solutions.

At the very end I passed out a make-your-own-globe paper that I found here. I demonstrated to the class how to make the globe, using these directions:

1. Cut around the 12 segments (gores) that make up the globe. Cut right in between the gores so your scissors almost touch the equator (the line running through the middle) but don't cut all the way through!

2. Roll the cut-out into a cylinder and tape together both ends of the equator where they meet.
3. Take four pieces of tape, cross two, cross the other two, then cross the two sets (so you've created an asterisk of tape) and place it on the pointed end of one of the gores, so the sticky side faces upwards.
4. Bend the other 11 gores into the middle, so the tips meet at the same point.
5. Stick them down firmly on the tape. This end should now be cupped.

6. Do the same with the gores at the other end to create a sphere.

Don't be disappointed if your globe is not a perfect sphere. It is actually impossible to recreate a perfect sphere from a simple template like this! In fact, at the beginning of the lesson, I told the kids we were going to attempt two impossible things. The orange peel projection was the first, and creating a 3D sphere from a 2D sheet of paper is the second!

Have fun making your globes. :)

ESRI UC Day 2--not an auspicious start

2011-07-12T10:01:00.001-07:00

Not an auspicious start to the second day at all. My suspicions about the weak showing of the conservation GIS community was confirmed at the first session I had planned on attending:

And at the second:

Hopefully the rest of the day will be better...?

ESRI UC Day 1

2011-07-12T09:41:00.000-07:00

The first day of the UC was informative, fun, and at times a little overwhelming. Jack and his colleagues were doing their thing at the plenary, and made a few announcements about 10.1 and ArcGIS Online that I found particularly noteworthy:

Dynamic legneds will be supported (finally!!)
Automatic image enhancement
Dynamic viewing of LAS files (LiDAR)
Right-click within an MXD to package and/or convert map into a service
ArcGIS online now supports a wide range of data import options, including drag-and-drop of CSV for point data (that was one of the coolest demos of the plenary)
ESRI is in the process of building a global, multi-resolution topographic mosaic that will also include user-contributed hi-res LiDAR. Not clear about when that will launch, but the data will be accessible as WMS *and* as points and rasters.

BEST NEWS OF ALL: ESRI is releasing 'ArcGIS Home' desktop + extensions for $100. The idea is to enable neophytes to get started, veterans to develop new skills, and anyone to use their software for volunteer projects.

Unfortunately, I felt like the message from ESRI at the plenary was WEB WEB WEB WEB and there was very little emphasis on any of the cool new analytical tools they are developing in the desktop, much less on how they're dealing with the huge list of bugs at 10.0 (for example, I still can't get dissolve to work, which is why I'm still about 90% in 9.3.1). I understand where they're coming from, but it would sure be great if they'd get the core functionality of their software working before they push us all into the bright shiny cloud-computing future.

Jack doing his thing at the plenary

After the morning plenary we had a two hour break, and after a great lunch with my former colleague (and current Cascade Land Conservancy GIS Manage)r Christopher Walter, I took in some of the sights of the waterfront, including the San Diego Maritime Museum. It was really great to finally explore the Surprise, a ship I've read so much about in Patrick O'Brian's novels.

The HMS Surprise!

The map gallery reception that afternoon was superb as usual, but it sure seems like there is far, far less representation of the non-profit world in general and the conservation GIS community in particular.

One of the many cool maps on display in the Map Gallery. How the heck did they create that symbology?!

At the 2011 ESRI International User Conference

2011-07-11T07:29:00.000-07:00

I'm here in sunny San Diego attending the 2011 ESRI International User Conference. After arriving and registering, I posted four CORE GIS maps in the Map Gallery: Lopez Island Potential Trail Corridors (created for San Juan County and the Trust for Public Land), California Coast Reslient Habitats, Greater Everglades Resilient Habitats, and Pacific Northwest Resilient Habitats (all created for the Sierra Club's Resilient Habitats Campaign).

I'm presenting on Thursday morning at 10:15 in Room 30E on the work CORE GIS did for San Juan County. My co-presenter is Breece Roberts of the Trust for Public Land. If you're here at the conference, please stop by and check it out.

I'll be posting throughout the conference and will include many more photos. I'll also post the occasional tweet, you can follow me at http://twitter.com/COREGIS.

CORE GIS posters all mounted in the Map Gallery

My ride during the conference

Friday Harbor Data Development Video

2011-03-22T16:57:00.000-07:00

I just got the link to the PPI Group Friday Harbor video I mentioned in the last post (thanks to Greg Sutherland at San Juan County) and you can watch it here.

NW WA GIS User Group Presentation

2011-03-22T16:16:00.000-07:00

The NWWAGIS User Group meeting in Bellingham on Friday was really great. There were lots of interesting people to meet and talk with (including a client I had not yet met in person!), some excellent presentations, and lots of good discussion.

An impromptu presentation by Greg Sutherland of San Juan County was particularly noteworthy--he showed a YouTube clip of a demo the PPI Group did for San Juan County Public Works. They showed up on the 10:00 am boat, drove their special data collection vehicle around Friday Harbor for a couple of hours, and prepared a demo by 1:00. They collected multi-angle high-resolution photos (similar to the Google StreetView photos) and a very dense LiDAR point cloud. The end result? Engineers are able to take measurements of rights-of-way, cross walks, stop signs, utility poles, you name it, all from a street-level photo. I think the video might be 'invite only' since PPI is courting San Juan county as a client, but once I find the link I'll post here.

My talk seemed to go fairly well, and I received some positive feedback afterwards and lots of helpful suggestions about some of the trickier analytical questions. Here is a PDF if you would like to check it out. Many thanks to Dan Siemann and all of the folks at the National Wildlife Federation for asking me to work on this interesting project, and the Mountaineers Foundation for providing some of the funding.

CORE GIS--Live!

2011-03-17T11:24:00.000-07:00

I will be giving a presentation tomorrow in Bellingham to the Northwest Washington GIS User's Group.

March 18th, 2011
9:00-12:00 am
City of Bellingham, Fireplace Room
625 Halleck St, Bellingham

Click here for a PDF map.

I'll be talking about some recently completed work I did for the National Wildlife Federation examining floodplains, flooding, and wildlife. I'll post the presentation here and on the website next week.

Great Data, Byzantine Retrieval System

2011-02-24T11:41:00.000-08:00

I am working on a series of maps for the Sierra Club's Resilient Habitat's campaign. The maps have been great fun and cover geography that I haven't mapped in awhile. The most recent map covers the Greater Everglades ecosystem, and since the habitat extent includes a substantial portion of the Atlantic ocean and Gulf of Mexico, we thought it might add visual interest to show bathymetry.

After doing a bit of research, I found a great source for integrated terrain and bathymetry at the NOAA coastal relief site. I found my area of interest, clicked on the link to download the data, and was somewhat surprised to see no obvious way to download the data--no 'download' button, no FTP link, nothing. I did notice a 'Create Custom Grid', but since I wanted all of the data shown in the map, that seemed like a hassle. So I called NOAA, and to my utter astonishment, reached an extremely helpful human being on my first attempt. She didn't know how to obtain the data either, but transferred me to someone who did.

Turns out, the ONLY way to obtain the data is by the 'Create Custom Grid' button, even if you want the whole enchilada. But it gets better--you can't specify the whole extent in the create custom grid dialogue, because the extractor limits your request to about 8,000 cells in either direction. So, I had to split the grid into fourths. Here are my notes outlining how to do that:

The grids are extracted and exported as ASCII text files, which I imported to ArcGIS GRIDs. But there's another catch: the upper value of each grid showed up as 65,535. This did not seem like a plausible elevation value (unless the Z values were in centimeters?!) so after a bit of Googling found this helpful post by Thomas Ballatore on the ESRI Support website. This is in response to someone working with SRTM data, but the same procedure worked equally well on the NOAA coastal relief data:

The SRTM files contain values from 0 to 65535. In a given SRTM tile, most of the values will be "typical" elevation values like the 1,133m and below you mention. However, areas where there is no data (voids) are assigned a value of 32768. The setnull command mentioned above would indeed set those values to "nodata".

HOWEVER, the SRTM data also correctly contains areas below sea level. These are reported as decreasing values from 65536. For example, an elevation of -2m would have a value of 65534, and elevation of -10 would be 65526 and so on.

For every country I have worked with that has a coastline, there will be a number of these along the coastline. Whether they are truly below sea level or if that is just an inaccuracy of the SRTM data would require further investigation.

Anyway, if you set all values greater than 1133 to nodata, then you will incorrectly set these negative values also to nodata. To avoid that, I use the following two steps in Raster Calculator to correctly prepare the SRTM data:

Step 1. Execute the following:

setnull([N30E119.bil] == 32768,[N30E119.bil])

where N30E119.bil is an SRTM file I was recently working with...change this to your tile's name. This will set the voids to nodata.

Step 2. Then execute this:

con([N30E119.bil] > 32768,[N30E119.bil] - 65536,[N30E119.bil])

This will correctly convert the negative values to negative values. Remember that spaces are important in raster calculator!

After running this on each of my four grids, I mosaiced them into a single grid, derived some hillshade, and was good to go.

Once the Florida Resilient Habitats map is finalized and Sierra Club has signed off on it, I will post it here.

The Ephemeral Nature of Maps in our Modern Age

2011-02-05T21:32:00.000-08:00

I've been thinking a lot about history these past several weeks, primarily because of the historic mapping work I described in an earlier post, but also because I am reading The Pirate Hunter by Richard Zacks. This excellent book is the true-life account of Captain Kidd, and it is based on painstaking research Zacks undertook for nearly three years, poring over historical documents, letters, diaries, newspapers, etc. Yes, it was time consuming and occasionally difficult work, but it was possible for Zacks to do the research because once he located a document, he could actually read it--or have it translated--and did not need to rely on any technology other than his eyes and grasp of archaic phraseology.

Captain William Kidd's 315 year old commission from the King of England

Similarly, but on a much more localized scale, I have been working with a client to recreate the land ownership pattern of portions of southwest Washington based on a digital scan of a hard copy map that was produced in 1891. This 120 year old map was created by hand with pen and ink, but it is remarkably accurate given the limitations of surveying and cartographic technologies available at the time. But similarly to Zacks, all we need to do is use our eyes to interpret the map and determine what was happening on the landscape back in the 19th century.

Let's contrast that with the current situation. Most of the maps we create are transmitted as PDFs, JPGs, or some other electronic format, and rarely printed out (maybe 5-10% are printed out). When they are printed, most of the non-profit organizations and government agencies do not have any clear system for cataloging and archiving the maps (or data used to create them) for posterity. Compounding the problem, more and more maps are completely web-based: the base layers might come from a variety of sources--Google, USGS, NOAA, NRCS, you name it--and the 'value-added' content might be coming from any number of other servers. The various layers are widely distributed across dozens of servers, and the underlying information is updated at varying intervals. How do you even capture a "snapshot" of an interactive map like that? What are the chances that the full functionality of any web map can be reproduced 120 years from now? I think very slim indeed, but perhaps I am being overly pessimistic.

The great irony seems to be that we now have access to more information than any other generation in history, but future historians will be able to access only a tiny fraction of it, because we are not doing a sufficient job of preserving it.

Obviously I am not the first person to surf this particular brainwave--for example, see here, here, here, here, and especially here.

Promoting Geographic Literacy

2011-01-31T16:43:00.001-08:00

I volunteer on the board of my son's Parent-Teacher-Student Association board. My role is to maintain and update the PTSA's website, but at a recent meeting one of the board members mentioned needing to find grant money to provide world maps to several classrooms in the school. My first thought was "How could it be possible that any classroom in any school lacks something as fundamental to a decent education as a world map?!?" My second thought was "Hey, I have a color plotter, and know a bit about maps..." and before I realized what I was saying had volunteered to provide all of the maps as a donation to the school.

I love designing maps and it would have been fun to create a world map from scratch; unfortunately, I did not have time for such a monumental undertaking, so decided to search for a decent, public domain map. I found one here at the World Factbook.

So far I have provided eight poster-sized versions of the map, and they seem to be a hit with the teachers and the students.

A couple of future world travelers in front of the printed map.

More Historic Mapping--Mt. St. Helens

2011-01-25T14:21:00.000-08:00

For over a year I have been working on a series of maps featuring Mt. St. Helens (MSH) and the surrounding region for both the Sierra Club and the National Parks Conservation Association. Both groups have been advocating some major changes to the management status of the current National Volcanic Monument (NVM), and the mapping has been used to support their lobbying efforts.

An interesting spin-off of this work is the recreation of historic land ownership patterns. In order to fully understand the current land ownership and management situation in and around MSH, it's important to have an understanding of the previous policy decisions that got us here. I have been working with Charlie Raines to develop a variety of data from historic maps (100 to 130 years before the present day) and it is really fascinating.

On a personal level, it is humbling to work with these maps that were created by hand--with pen, ink and paper--before there were aerial photographs, orthophotos, satellites, even NAD 27! These old maps georeference remarkably well with the modern-day USPLS townships and sections.

However, there have been some major changes to this landscape over the past 100 years, both natural and man-made. Mt St Helens lost over 1,300 feet of elevation as a result of the 1980 eruption, and we humans built roads, railroads, and numerous large reservoirs on the Lewis, Cowlitz, Nisqually, Bumping, and Columbia river systems. As part of the historic mapping process, I've had a lot of fun 'reversing' these changes by deleting the reservoirs, re-drawing the rivers in their original channels, and erasing highways and interstates.

These maps are still a work in progress so I cannot share them just yet, but here are a couple of screen shots to give you a feel of the historic/modern juxtaposition.

A "split-screen" view, showing an 1891 Northern Pacific Railroad land grant map on the left, and the modern CORE GIS map on the right. Note the fold in the historic map running right-to-left between the 'river' label on the left and Swift Reservoir on the right. Click on thumbnail to embiggen.

Another view of the Northern Pacific Railroad land grant map, this one focused on the region around Mossyrock.

Modern-day view of the same extent.

Hiking Washington's History

2010-10-19T13:58:00.000-07:00

Last year I worked on a series of 51 black and white maps for author Judy Bentley's book Hiking Washington's History.I received my copy in the mail today, and it looks great! The published size of the maps is a bit smaller than the versions I produced, so some of the text is a bit difficult to read, but on balance I'm quite happy with the finished product.

In a future post, I'll write about the unique challenges associated with black and white cartography.

Click on images to embiggen.

Biggest Map, Smallest Map

2010-10-11T14:25:00.000-07:00

The week before last I worked on two maps for two different non-profit organizations focused on wilderness protection: The Wilderness Society and the Washington Wilderness Coalition. TWS needed a thumbnail of a map for a newsletter; WWC needed a giant backdrop map for a display they are putting together with a graphic designer. As it turns out, the TWS map is the smallest map I have ever made (2.5" x 3") and the WWC map is the largest I have ever made (60" x 45").

Here is an image to give you a sense of the difference.

Biggest on left, smallest on right. Click on thumbnail to embiggen.

Excellent article about GIS in NY Times

2010-02-17T11:38:00.000-08:00

The NY Times published this very intriguing piece about GIS earlier this month. It focuses primarily upon urban design and architectural applications, but it's nice to see the technology getting such prevalent exposure.

WA URISA Conference

2009-05-11T11:00:00.000-07:00

Last week I attended the Washington URISA conference for the first time. Overall, I found the conference to be informative and useful and was impressed by the variety of sessions, particularly the volume and quality of open source presentations. I presented with David Howes and Gretchen Peterson on the Lone GIS Professional, a group that David started last year. It was an interesting session, in that about 1/2 the time was allotted to group discussion and David recorded audience input in real-time. The objective of the talk was to spread the word about the Lone GIS Pro group, get more people involved, and perhaps more importantly, find out what would be helpful to Lone GIS people.

It was surprising to me how many attendees of the conference are Lone GISers--either solo practitioners or the only GIS person at their business/agency/non-profit. The need for (and value of) a group like the Lone GIS Pro was reinforced in many of the sessions, based on their heavy emphasis on enterprise GIS systems with massive budgets, staff, and procedural requirements. It really is a differnet world when you're working on your own, and I'm grateful to have such an active, energetic and helpful group to turn to when I have a question or need some backup.

If you are a Lone GIS professional and are interested in joining the group, please email me--the group is invitation-only.

From Images to Data--Image Segmentation

2009-04-13T09:53:00.000-07:00

Last year I searched for freely available image segmentation software as an alternative to eCognition. My original search was related to a project that I decided not to pursue; however, this past fall and winter I worked on a project that required image segmentation . So, after doing additional research, I was able to determine that Brazil's National Institute for Space Research (INPE) produced a freeware program called SPRING that does image segmentation. The USFWS worked with INPE to produce an English translation of the software, along with a manual available here. The software itself can be downloaded here.

After working with this software for the better part of a day, I was able to get fairly decent segments out of my imagery, but the classification was not very good. I also found the software difficult and counter-intuitive to use, and although it is ‘translated’ a lot of the menus don’t make much sense.

So I started searching again and found Berkeley Image Segmentation which is great. It is commercial software, but I was able to get the beta release for $900. The creator of the software, James Scarborough, was surprisingly accessible and extremely helpful anytime I had a question about what the software was doing. He has already integrated several of my suggestions into the most recent version, and I’m sure he’ll continue to solicit and incorporate user suggestions. The software is much, much easier to use than SPRING, and it has several classification options built in (K-means, K-nearest neighbor, and neural networks) and while they are better than SPRING they still weren’t quite good enough. James suggests in the ImageSeg manual using WEKA for segmentation classification. This is open-source data mining software, and I used the expectation maximization clustering algorithm with great success, but there are many others available.

I have sample output on the CORE GIS portfolio page, along with a brief description of one of the projects for which I’ve used it (third one from the top).

Park(ing) Day in Seattle

2008-09-22T14:17:00.000-07:00

Park(ing)Day took place on Friday, September 19, and was a "one-day, global event centered in San Francisco where artists, activists, and citizens collaborate to temporarily transform metered parking spots into “PARK(ing)” spaces: temporary public parks." The Trust for Public Land hired CORE GIS to create a map of the park locations in Seattle, to hand out to curious passers-by and help people find the various parks.

This photo of one of the parks was taken by Jeanine Anderson.

Sustainable Ballard: Local Food Production and Population

2008-07-30T08:58:00.000-07:00

CORE GIS is located right on the edge of the Ballard neighborhood in Seattle. The non-profit Sustainable Ballard has been active in numerous sustainability and environmental issues, and each year at this time they ramp up their "Eat Local" campaign by promoting the 100 mile diet.

This seems like a great idea, for a number of reasons--it supports local farmers and local economies, reduces fossil fuel consumption, builds community, and encourages all of us to think about where and how our food is grown.

I decided to take this idea to its logical extreme--what if everyone in Seattle decided to follow the 100 mile diet? Do we have enough agricultural land to support that many people?

I started with 2000 U.S. Census data, specifically the SF1 100% population count at the block group. Then I used 2001 NLCD land cover data and extracted the two agricultural classes--cultivated crops and hay/pasture. I arbitrarily chose a spot in the middle of Seattle, created 50 mile and 100 mile buffers, then counted up the number of people and the acres of agricultural land within the two distance bands.

As it turns out there is far less acreage in cultivated crops than in hay/pasture, and within 50 miles, each acre of cultivated crops would need to feed 172 people! If we assume that all of the hay/pasture can be converted into cultivated crops, the number of people supported by one acre drops to 22. Moving out to 100 miles improves the situation, with just under 31 people per acre of cultivated crops and just under 7 per acre for all agricultural land. (The cartographic and tabular results are shown in the thumbnail image to the right; if you'd like to download a screen-resolution PDF of the 30"x36" poster, just click here. Please contact me if you'd like a printed version).

However, according to one study, a meat-based diet requires 9 acres per person! A diet that is primarily plant-based (with some milk, cheese, and eggs) requires 3/4 of an acre. Clearly, we still have far too little agricultural land within our 100 mile radius to feed our entire population.

This suggests to me that our region has a lot of thinking to do about our food security and food sovereignty. What happens if there are shortages of fossil fuels, in particular diesel, for transporting food across the vast distances it currently travels? Are there areas within our region that have prime agricultural soils that are not being cultivated? What policies can/should be put in place to ensure that we have the capacity to feed a much larger proportion of our population from local farms? How should our food distribution network change to make it easier and more efficient for local farmers to get their produce to market?

Stemilt Partnership

2008-03-31T08:41:00.000-07:00

For the past several months I've been working with the Trust for Public Land on the Stemilt-Squilchuck Community Vision. Our client is Chelan County, and we've been working closely with a large citizen group known as the Stemilt Partnership. This photo was taken just after our most recent Partnership meeting last Wednesday at the Malaga Fire Hall. The project started in response to a proposed land exchange in which the Washington Department of Natural Resources was planning to divest itself of four sections in the upper part of the basin. As it happens, these four sections form the central core of many of the land use and land management activities that affect the entire watershed. The Partnership was formed to help the County determine what should happen with the land in light of all of the stakeholder groups that are using these public lands.

This project has been particularly interesting for me to work on, because it contains all of the elements that I really love about my job--interesting data and modeling challenges, lots of cartography, the opportunity to meet with and learn from a wide range of citizens and agency people (farmers, real estate developers, wildlife biologists, policy wonks, etc), public speaking and lots of travel to the watershed. The timeline is fairly compact for a project of this size and complexity, but I think the fact that so many community members are heavily engaged will help us produce an excellent result.

Chuckanut Mountains Park District Map

2008-02-23T08:50:00.001-08:00

I recently completed work on a map for the Chuckanut Mountains Park District. This was a quick, fun project I did for Ken Wilcox and the other folks involved in establishing a more coherent and comprehensive land management approach for this unique region. The Chuckanut Mountains are the only place where the Cascade foothills come all the way to salt water.

The map shows 2006 NRCS NAIP 1 m color orthophotography, major public land owners (derived from the Snohomish and Skagit County parcel databases), as well as all private parcels 10 acres or larger in size.

I wish the CMPD well, and I hope this large poster (40" x 60") is helpful in accomplishing their mission.

Mauritius--A Projection Challenge

2008-02-09T20:22:00.001-08:00

Recently, I was asked by one of my clients to project a bunch of data for the island nation of Mauritius in preparation for some wetlands-related field work they will be doing there. They received the data from the national government, and there was no projection information included with the data.

As it turns out, Mauritius has its own grid, which is independent from all other geographic coordinate systems and is not natively supported by ArcMap. According to a map I found on the Government of Mauritius web site, the projection is as follows:

Grid : Mauritius
Projection : Lambert Conical Orthomorphic
Spheroid : Clarke 1880
Unit Of Measurement : Metre
Longitude of origin : 57°31'18.58" East of Greenwich
Latitude of Origin : 20°11'42.25" South
Scale Factor at Origin : Unity
False Co-ordinates of origin : 1,000,000m Easting
1,000,000m Northing

Unfortunately, Lambert Conical Orthomorphic is not available in ArcMap, but through my research I determined that Lambert Conformal Conic is a very close approximation. So, converting the above description into ESRI lingo, it looks something like this:

Projected Coordinate System: Mauritius
Projection: Lambert_Conformal_Conic
False_Easting: 1000000.00000000
False_Northing: 1000000.00000000
Central_Meridian: 57.52183000
Standard_Parallel_1: -20.19507000
Standard_Parallel_2: -20.19507000
Scale_Factor: 1.0
Latitude_Of_Origin: -20.19507000
Linear Unit: Meter

I punted on the Standard Parallels, assuming that the island is small enough for the latitude of origin to suffice for both parallels. This sort of worked, and I placed the GTOPO global DEM in the map frame with the newly projected data, resulting in the first image. Seems close, but a bit hard to tell.

So I downloaded SRTM data for the island, which has much higher resolution than GTOPO, and the result is the second image. Clearly, pretty far off. At this point, I was getting in over my head with respect to creating custom datum/spheroid combinations, so I called the good folks at ESRI and after an hour on the phone, they helped me to build a very solid projection and transformation for Mauritius (this is the actual PRJ file, please feel free to use it, just remove the carriage returns after each comma before saving as a PRJ):

PROJCS["Mauritius_lambert",
GEOGCS["Mauritius",
DATUM["",
SPHEROID["Clarke_1880_RGS",6378249.145,293.465]],
PRIMEM["Greenwich",0.0],
UNIT["Degree",0.0174532925199433]],
PROJECTION["Lambert_Conformal_Conic"],
PARAMETER["False_Easting",1000000.0],
PARAMETER["False_Northing",1000000.0],
PARAMETER["Central_Meridian",57.52182777777779],
PARAMETER["Standard_Parallel_1",-20.19506944444445],
PARAMETER["Standard_Parallel_2",-20.19506944444445],
PARAMETER["Latitude_Of_Origin",-20.19506944444445],
UNIT["Meter",1.0]]

The custom datum comes from the Le_Pouce_1934_TO_WGS_1984 transformation ESRI helped me to create, which is here (again, remove CR after commas, save as a gtf file):

GEOGTRAN["Le_Pouce_1934_TO_WGS_1984",
GEOGCS["Mauritius",DATUM["",
SPHEROID["Clarke_1880_RGS",6378249.145,293.465]],
PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],
GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",
SPHEROID["WGS_1984",6378137.0,298.257223563]],
PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],
METHOD["Geocentric_Translation"],
PARAMETER["X_Axis_Translation",-770.1],
PARAMETER["Y_Axis_Translation",158.4],
PARAMETER["Z_Axis_Translation",-498.2]]

The result is a very nice agreement between the red coastline vector and the SRTM topography, shown in the third image.

Alpine Lakes Wilderness Additions Introduced in Congress

2007-11-16T10:08:00.000-08:00

We recently completed work with The Wilderness Society, the Alpine Lakes Protection Society, and Congressman Dave Reichert's office to map proposed additions to the Alpine Lakes Wilderness Area. The proposal also includes the designation of the Pratt River as a wild river. One of the CORE GIS maps produced in this effort is featured in the photo of Congressman Reichert announcing the legislation. Hopefully this bill will get signed into law!

Excellent Source for Historic Census Data and GIS Files

2007-10-29T10:07:00.000-07:00

I am currently working on a project for The Trust for Public Land in the North Coast of Oregon, part of which involves an analysis of development patterns and trends. In working up numbers for population and housing units, I came upon an excellent source for historic U.S. Census data, the National Historical Geographic Information System. They provide access to the complete Census database for all of the decennial censuses back to 1970, as well as geographic boundary files for mapping the data. So far it has proven to be quite a goldmine!

Wenatchee Watershed Vision is Available for Download

2007-10-11T09:59:00.000-07:00

The Trust for Public Land recently released the Wenatchee Watershed Vision. According to the website, this document "lays out a bold vision - one that will require broad coalitions, strategic partnerships, and community initiative to be successful. TPL hopes the Wenatchee Watershed Vision will inspire community action to protect the special places and character of a landscape so many people love."

The GIS analysis for this project was started at CommEn Space and finished at CORE GIS. We also did the report layout and graphic design, which was a fun and slightly different challenge. The report and the maps produced for the report can both be downloaded here.

Measure 37 Maps are Available on Sightline's Daily Score

2007-10-05T09:54:00.000-07:00

CORE GIS recently completed work on a series of maps and analyses of Measure 37 Claims in Oregon. There is a map of the Portland Metro Region, the Central Willamette, Hood River and Wasco Counties, and the Hood River Valley. Eric de Place has some excellent analysis and commentary on the numbers we generated for Sightline.

CORE GIS is nearly a year old!

2007-09-27T09:50:00.000-07:00

CORE GIS will be a year old as of November 1st. I've decided to start a blog here on the CORE GIS web site, to share interesting news items and useful information. I'm using Wordpress, and will be experimenting with the features and layout over the next several weeks.

Stay tuned for more!