The GIS Guy

"Simple" Centroid Calculation

Mon, 19 Mar 2007 13:43:00 MST

1. Select any vertex and use it as a vertex for the n-2 triangles that are produced when this vertex is connected to each of the other vertexes. 2. Calculate the coordinates of the centroid for each of the triangles produced using this formula: XC = (X(1) + X(2) + X(3))/3 YC = (Y(1) + Y(2) + Y(3))/3 > 3. Calculate the area of each triangle produced using this formula:
[(X(2) - (X(1)) * (Y(3) - Y(1)] - [(X(3) - X(1)) * (Y(2) - Y(1))]/2 (areas may negative! ... for reas...

No SVG support for IE 7 and beyond

Wed, 14 Mar 2007 15:48:00 MST

I've seen several homemade and open source GIS demos that rely on SVG output for vector display in a web browser. Firefox and Opera support SVG natively, but until now, Internet Explorer users have relied on a plugin from Adobe. At this point it's old news, but Adobe is discontinuing support for their plugin which isn't really supported on Vista, either... so there's no SVG support in IE 7. From blogs, it looks like the product team is trying to figure out if they're going...

deCarta AJAX API

Tue, 13 Mar 2007 13:09:00 MST

I signed upforthe deCarta developer program today to try out their AJAX and Web services APIs. Looking around, it appears that their technology may be behind some of the bigger names in Web-based Location Based Services. Pretty cool. The API looks nice and straightforward, though it may be a little light. It's pretty new from the look of it. I like the map styling capability. I could imagine that some RPG/movie/console gamingfolks would go nuts with that. Create a look-and-feel that fit H...

Article on GIS and Accessibiliy

Thu, 08 Mar 2007 10:24:00 MST

Today, Directions published an article of mine on GIS and Accessibility for blind and visually impaired users. It's an off-mainstream topic, but given the ageing workforce issues that the computer industry at large is encountering, it's relevant....

Google Traffic data

Wed, 07 Mar 2007 11:45:00 MST

Directions reports this week that Google Maps and Google Mobile Maps now have traffic data layers for some major cities. There is much speculation over how they are doing it... I imagine they are getting some webservice traffic data from these major metro areas, but I could conceive of them using news/accident feeds or other tools to approximate the conditions, as well. What will they do next? Try this link for San Francisco traffic: http://maps.google.com/?z=10&ll=37.779399,-122.4192...

Expanding the GIS Universe through Open APIs

Thu, 11 Jan 2007 20:59:00 MST

Today's Directions Mag will feature another article I wrote on the changes in the GIS industry driven by the Open API tool kits being offered by Google, Yahoo, Microsoft, and others. I tried to stay away from the negatives regarding the traditional GIS companies and where they are headed, but I will add this: If ESRI, MapInfo, AutoDesk and others don't start offeringusable free data along with their Web mapping products, they will continue to lose market share to the GYM types. Even t...

GeoMedia Free Version

Thu, 04 Jan 2007 12:05:00 MST

Seems like Intergraph's GeoMedia has improved greatly in the last few years, but I wish they would put a time limited version out there so that people like me could actually test drive it. I'm not sure why the major vendors are making it harder to test drivetheir software.Given the grassroots growth in the GIS industry driven by the open API and opensource GIS software, you would think thatthe Intergraphs and ESRIs would give out more software to try to hold onto their marketshare....

Types of Testing for Requirements

Thu, 04 Jan 2007 11:44:00 MST

Software and system requirements should be testable. The four types of tests that can be used to validate a requirement are analysis, demonstration, inspection, and testing. Any one requirement may be validated according to any of these four methods. Analysis - ...

Brief Survey of Online Mapping Blogs

Thu, 07 Dec 2006 10:40:00 MST

Adena at Directions Magazine published a good, quick survey of some of the online mapping blogs. It will be interesting to see where this stuff goes....

Geospatial directory websites

Fri, 01 Dec 2006 10:43:00 MST

As the number of public websites that use Open API's increases, we'll see more directory websites that operate as passthroughs to those sites. The important thing will be for people to be able to distinguish between sites that operate merely as portals for click-through revenue and sites that are honest catalogs of information for the geospatially curious. > YakJive has been listed in the

Another Article Published Today

Thu, 16 Nov 2006 10:13:00 MST
I had another article published today. Just fun to see that it's not all vanity publication, like this site! This article was on using Open Source GIS as an alternative to proprietary GIS tools. I think the ESRI suite has gotten so complicated that it's going to eventually collapse under it's own weight. Frankly, they're too focused on license sales and not enough on actually satisfying their consumer base. The OSS alternatives are sure to eventually step in and take over. C&...

GPS File Format Converter

Thu, 16 Nov 2006 05:44:00 MST
Poking around in the GPS space this week, I noticed that there are 100's of GPS file formats out there. Kind of unbelievable. While I'm going to convert YakJive to allow people to upload and display GPX and possibly KML files, I can't do everything. Fortunately, this nice guy named Robert Lipe has taken it upon himself to build a free GPS file format converter called GPSBabel. I'll definitely be recommending it to YakJive users....

Cool Satellite image of the Luxor

Fri, 10 Nov 2006 21:55:00 MST
I stayed at the Luxor this week in Las Vegas for a conference. Check out this cool, reflective photo of it on Google Maps. ...

Welcome!

Fri, 10 Nov 2006 21:48:00 MST
Welcome to a hobby site dedicated to mapping, GIS, and anything else technical that interests me. You'll find here some of the articles that I've published (with links back to the original, of course) and a variety of cool tools and sites that I've found. Along the way I'll also post some articles related to different places on the Earth so that I can show some cool YakJive functionality....