Monthly Archives: July 2009

New Hard Drive for GIS Data

iomega_prestigeTo lighten the load on my main hard drive, I decided to move my burgeoning GIS data warehouse onto another drive and bought my first Tera Byte drive (Iomega Prestige). After plugging it in, I soon came to realize that due to conflicting definitions of TB (1000GB or 1024 GB), Windows was only seeing 931GB of free space on my brand spanking new drive – Wow ! What a let-down !

Anyway, I’m going to be moving most of my GIS data onto the new drive so that I can carry it with me and access it from the laptop.

One thing to consider and spend some time on researching is how to organize all this GIS data. Now, is the time to give this some thought. I’ve noticed recently that I’ve been downloading and copy/pasting several GB every day. To keep the chaos at bay, I need to come up with a permanent system.



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Playing Around with GPS

pn40I’m thinking about buying an affordable GPS unit. Not as a techno toy but an educational tool. I am looking for something that will work well for exchanging (up/downloading) with GIS. Downloading GPS is obvious. But something will allow easy uploading of GIS data, e.g. shapefiles or raster data. The DeLorme Earthmate PN-40 Handheld looks pretty cool. Sounds like it will allow me to upload all kinds of data and even selectively display this data as layers. But the last thing I want is to be limited by another piece of software from Delorme for all this data exchange. Need to see if that is necessary.

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Using a DOS command…

I can’t believe I just googled how to copy files in DOS. But turns out that was way easier than copy/paste job under Windows. After downloading all those DRGs the other day, I ended up with a bunch of other files that I didn’t want – scattered among the *.tif’s  across a few hundred file folders.

To make things easy, I used:    xcopy c:\origin\*.tif c:\destination.

I had almost forgotten how much fun DOS used to be !

Or if you’d like to merge a bunch of files from different directories in one folder.

for /r c:\…\origin %i in (*.tif) do copy /y %i c:\…\destination

and for those darn temp files the downloader created (*****.tif.temp), I used:

ren c:\origin\????????.???.??? ????????.tif – one “?” for each character in the file name.

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GIS Programming Challenge with DRG files

Time for a programming challenge for myself as the budding programmer. This week, I downloaded a number of USGS topo DRG’s for the state of Texas. A little tool I found somewhat helpful (after a few failed attempts) was Pagenest, a free, little offline browser/downloader.

Now, I am able to display the topo map for an entire area of intererest. Unfortunately, these are NOT collarless maps. So one thing to find out is how to get rid of the collar or – if possible – how to hide it. The programming challenge will be to come up with a way that allows me to display the appropriate USGS topo map for the extent shown in ArcMap at the click of a button. I am running a script that adds the correct TIFF file (fortunately the naming convention for these files indicates their geographic location) to my data frame based on the boundary coordinates of the current extent…

Frankly, I have no idea how to do this. That’s why it’s the programming challenge of the month !

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DEM (digital elevation model) Files & Spatial Analyst

contourSo, I’m trying to get the most out of my 60-day trial of ESRI’s Spatial Analyst. I finally downloaded a DEM file from GIS Data Depot. The file I ended up with was a 2.5 MB tarball (TAR.GZ)… I’ve never had to open one of those before in Windows (unlike during my Ubuntu adventures). So I installed 7-ZIP to unzip (I love small programs like that!). Then I had to convert the unzipped pile of DDF’s into a DEM using SDTS2DEM.exe. Finally, I could open the DEM in ArcMap, build pyramids, and display the surface. Then I contoured and compared the contour lines with those from the USGS DRG TIFF, and they were remarkably similar. Wow, DEM files are pretty neat. I hope that we can get a full license of Spatial Analyst soon.

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USGS DRG (Digitized Raster Graphic) Files

Somewhere in Dallas, Texas...
Somewhere in Dallas, Texas…

I’ve written on this blog before about the difficulties of teaching yourself GIS when much of your day-to-day grind (in a non-GIS company ) doesn’t confront you with GISsable challenges. Well, turns out it’s only a question of trying a little harder. Here is a simple example of daily-grind-education…

One of our engineers was looking for a USGS topo map this morning. Of course, I was asked: “Can’t you get me one with GIS ?” My first reaction was to say: Probably … but I’m not sure I have the data for that. ( I had been looking for sources for DEM files the other day without location any free data.)
During lunch, I started browsing the latest addition to my GIS library
Desktop GIS: Mapping the Planet with Open Source Tools, and on page 4, it mentions a free source of DRG files:
Needless to say, it took about 5 minutes to find, download, scale, and print the needed section from the topomap, hopefully make everyone happy, and add another simple task to my growing arsenal of GIS weapons. Okay, I didn’t save the planet. But I felt like I learned something useful.

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The Evolving Geoweb

Here is a pretty good overview of the evolving geoweb (Where2.0) scene, talking about the market players and technologies.

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