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Great Introductory GIS Tutorial And Screencast Series

Published at October 15, 2009 in GIS. 4 Comments

The Department of Land Affairs, Eastern Cape, South Africa has created a terrific tutorial series on GIS called “introducing GIS”. PDF worksheets and video screencasts cover topics like vector and raster data, attributes, topology, coordinate systems, map production and spatial analysis in a clear and easy-to-follow fashion. The worksheets are freely distributable under the terms of the GNU Free Documentation License, while the screencasts are released under Creative Commons. While you can watch the screencasts in your browser, they are a bit small – I would recommend downloading them so that you can open them in a stand-alone video viewer that you can resize to larger dimensions for easier viewing. Right-click on the video link and choose “Save as”. For that matter, if you download all the screencasts and worksheets and put them on a DVD, you have a great educational resource to share and distribute.

The site has a custom Windows installer of the open source GIS Quantum GIS, including the data presented in the tutorials. However, Quantum GIS also runs on Mac and Linux, and they offer the tutorial data as a separate download; find the link at the bottom of the web page. For that matter, the Quantum GIS Windows installer they have is version 1.0.2, while the most recent stable release version for Windows is 1.2.0-1. So even if you have Windows, you may want to download the data separately, and install the most recent version of Quantum GIS using the osgeo4w installer.




Quick GPX Viewing In A Google Maps Interface With GPXViewer

Published at October 14, 2009 in GPS, GPX and Google Maps. 0 Comments

It’s nothing fancy, but Zonum’s GPXViewer website lets you upload a GPX file (points and tracks), and then quickly plots it in a Google Maps interface:

gpxviewerz

No editing, export or additional info in this app, just display; but Zonums has other web apps like Digipoint and MapTool for that.




Put Custom Startup Graphics On Your Garmin GPSr Unit

Published at October 13, 2009 in GPS and Garmin. 0 Comments

Art writes about his programs Garmin 60CSx Whiz, Garmin Colorado Whiz and Garmin Oregon Whiz, which modify the firmware on a Garmin GPSMap unit to display a custom startup image and other alternate graphics. 60CSx-supported units include:

  • Garmin 60Cx
  • Garmin 60CSx
  • Garmin 76Sx
  • Garmin 76CSx

The interface looks straightforward enough (graphics from the program website):

60CSxWhiz_Art colwhiz Oregon_Whiz

Sample graphic images are provided for the 60CSx whiz, but you can also use your own (love the kookaburra):

60CSx_Examples

And apparently they do what they’re supposed to:

60CSx_Mod

I say “apparently” because I’m too chicken to try it out, even though Art has a pretty solid hack programming resume. But if any braver souls want to give it a try and post their results in the comment section, have at it!




Open Source .Net Control For Map Display

Published at October 12, 2009 in Web apps. 0 Comments

I’m not a .Net programmer (I’m still stuck in the primordial ooze that is VB6), but if you are, you might want to check out GMap.Net, a free and open source .Net control for embedding online map services in Windows applications. You have the option of displaying maps from Google, Yahoo, OpenStreetMap, Bing or ArcGIS, with tile cacheing an option for faster performance. Several demo apps are available to show what you can do:

GMap.Net

One quick tip: right-click and drag to pan the map (took me a while to figure that one out).




Get A Point Position With GetLatLon

Published at October 8, 2009 in Google Maps and Web apps. 2 Comments

GetLatLon pretty much does exactly what its name implies – gives you the latitude/longitude of a point in a Google Maps interface. A crosshair at the center of the display marks the position for which coordinates are given at the bottom:

getlatlon

Digipoint can perform the same function, plus many more, but if all you need is a coordinate position, GetLatLon has a stripped-down simplicity that makes it easier to use. Just keep in mind that coordinate positions in Google Maps can be tens of meters off from the true position (see here and here).

Via Download Squad.




Embeddable US Demographics Map

Published at October 7, 2009 in ESRI, Web apps and data. 1 Comment

As a demo of the ArcGIS API for Flex, ESRI has a new page that lets you create an embeddable/shareable map of demographic data by US county. Only seven datasets available now:

  • Median Household Income
  • Population Change 2000-2009
  • Population Density (per sq. mile)
  • Median Home Value
  • Unemployment Rate
  • Average Household Size
  • Median Age

Map creation is trivially easy – select the demographic dataset from a dropdown, zoom the map to the desired extents, set a map size in pixels, and you’re done; links to a map with your parameters, and code for an embeddable map, are generated automatically. Here’s an embedded map, scrollable and zoomable; unemployment rate is the defaultdataset, but you can choose other sets with the dropdown menu at upper right:

More datasets would be nice, as would control over colors and ranges …

Via GIS And Science.




Online Resources For Magellan Triton GPS Owners

Published at October 6, 2009 in GPS and Magellan. 0 Comments

The huge number of online support resources for Garmin handheld GPS units dwarfs the number of comparable  sites for info and data for the Magellan Triton GPS line. Still, there are a few very useful sites to bookmark if you own this raster-compatible GPS unit.




Any WordPress-PHP-Apache Gurus Out There?

Published at October 5, 2009 in blogkeeping. 3 Comments

Switched over the Free Geography Tools site on Friday to a new dedicated VPS, from the increasingly crappy shared hosting service. Generally, it’s running OK, but I’ve seen some odd behaviors, and I don’t have enough background in this stuff to know what’s going on. If any of you have any ideas as to what might be going on, or suggestions on things to try, I’d appreciate it.

1. In the suphp_log file, there are countless entries that look like this:

[Sun Oct 04 22:01:26 2009] [info] Executing “/home/freegeog/public_html/index.php” as UID 511, GID 511
[Sun Oct 04 22:01:26 2009] [info] Executing “/home/freegeog/public_html/index.php” as UID 511, GID 511
[Sun Oct 04 22:01:26 2009] [info] Executing “/home/freegeog/public_html/index.php” as UID 511, GID 511
[Sun Oct 04 22:01:26 2009] [info] Executing “/home/freegeog/public_html/index.php” as UID 511, GID 511
[Sun Oct 04 22:01:26 2009] [info] Executing “/home/freegeog/public_html/index.php” as UID 511, GID 511
[Sun Oct 04 22:01:26 2009] [info] Executing “/home/freegeog/public_html/index.php” as UID 511, GID 511
[Sun Oct 04 22:01:26 2009] [info] Executing “/home/freegeog/public_html/index.php” as UID 511, GID 511
[Sun Oct 04 22:01:27 2009] [info] Executing “/home/freegeog/public_html/index.php” as UID 511, GID 511

i.e. multiple attempts to execute the WordPress index.php file within a very short span of time. I get roughly four times as many of these attempts as I get actual visitors. It’s odd, since this file only loads in the wp-blog-header.php file, nothing else:

<?php
/**
* Front to the WordPress application. This file doesn’t do anything, but loads
* wp-blog-header.php which does and tells WordPress to load the theme.
*
* @package WordPress
*/

/**
* Tells WordPress to load the WordPress theme and output it.
*
* @var bool
*/
define(’WP_USE_THEMES’, true);

/** Loads the WordPress Environment and Template */
require(’./wp-blog-header.php’);
?>

No other WordPress files access or load the index.php file, so I’m at a loss as to why there would be so many attempts to execute this file relative to the number of site visitors.

2. A possibly-related problem is that at short and irregular intervals (between 5-10 minutes), the visitation rate to the site drops down to virtually nothing for about a minute or so, then pops back up again to a normal rate. Not sure what this is due to – perhaps a resource crunch from all those index.php executions?

What I’ve tried so far, without success:

  • Apache service restart
  • Full server reboot
  • Turning off all WordPress plugins
  • Switching to a different WordPress theme
  • Re-installing the last WordPress upgrade (2.8.4)

None of these seem to have had any effect. I’m baffled, but given my limited knowledge of these issues, that’s not hard. Anybody have a suggestion as to where to start?




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