Monthly Archives: June 2009

The Awesome Power of GIS (Google Mapmaker)

Here is a short post about the power of GIS. Iranians creating otherwise difficult to get maps of Theran using Google Mapmaker. It’s the GIS version of the Twitter stories coming out of Iran in recent weeks. Makes you realize that here and there among all the techie hype and web gimmicks, there are some really powerful ways to use technology. Few and far between, these actually manage to make the world a better place.

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Python Script for Spatial Analyst, License Error

I have been trying to get a little Python script from this tutorial to run for and hour, and kept getting errors:

import arcgisscripting
gp = arcgisscripting.create()
gp.workspace = “c:/users/arne/downloads/Python_ArcGIS_Lessons/Lesson2/Lesson2”
gp.overwriteoutput = 1

gp.select_analysis(“flowline.shp”, “RBCreek.shp”, ‘ “GNIS_Name” = \’Red Butte Creek\’ ‘)
gp.buffer_analysis(“RBCreek.shp”, “RBCreekBuff.shp”, “100”)
gp.PolygonToRaster_conversion(“RBCreekBuff.shp”, “FID”, “BuffGrd”, “CELL_CENTER”, “NONE”,  “30”)
del gp

RESULT:

Traceback (most recent call last):
  File “C:\Users\….\xxxxxxx.py”, line 15, in <module>
    gp.PolygonToRaster_conversion(“RBCreekBuff.shp”, “FID”, “BuffGrd”, “CELL_CENTER”, “NONE”,  “30”)
ExecuteError: Failed to execute. Parameters are not valid.
ERROR 000824: The tool is not licensed.
Failed to execute (PolygonToRaster).

Based on google searches for “ERROR 000824: The tool is not licensed.” I tried turning on the Spatial Analyst under ‘Extensions’ in ArcCatalog and ArcMap. I could never get it to work.

SOLUTION
Finally, I found this page here. Apparently you have to “turn on” Spatial Analyst from within the Python script by adding the line:

gp.CheckOutExtension(“Spatial”)

That finally worked !

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All the GIS Software in the WORLD !!!

Here is a comprehensive (?) list of commercially available GIS packages. Some of these I had never heard of. Here is a list of free GIS packages. Just a neat little overview of the market.

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From here to GIS Guru

I probably need to post this on some GIS discussion board… if you had 2 years time and a few $1000 to spend, what would be the smartest use of time and money to turn yourself into a GIS guru ? What software should you learn to use or buy, what training should you invest in ? What will be the trends over the next few years or so ?

UPDATE

I have gotten 2 pretty good responses to my post on thegisforum.com.

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GIS File Formats

I was googling and found this wikipedia summary of GIS file formats – quite useful, I thought.

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ArcMap – Legend Limiter Extension

I installed Legend Limiter the other day – a very useful tool that unclutters your map legends by only including those records shown in your layout, e.g. you don’t end up with a geology map for north Texas with a legend that includes Big Bend rocks ! The only other way I knew how to do this was to make a selection of the rocks I was interested in, export as a layer, and then include that layer on the legend. Now, all I need is figure the problem described in my last post, and how to have the legend put the geologic formations in chronological order.

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ArcMap – Labeling Map Legend w/ 2nd Attribute Table Records

Here is a little problem I’ve been having in ArcMap: When I create a geology map, I am using a geodatabase with the Geologic Atlas of Texas (GAT_250K-es.mdb) that contains digitized rock units and faults. This allows me to create great looking geology maps all over the State of Texas. A second geodatabase (GAT_Rockunit_Tables.mdb) includes additional attributes of the units and formations included in the first one, such as a description of the lithology.

What I would like to do but have been unable to figure out up to this point is to plot and label my geologic units on a map using MDB#1 but then label them in the legend using an attribute from MDB#2. It’s easy to join the two tables. But I can’t figure out, how to label the legend without also changing the labeling on the map. On the symbology table of the rock unit layer, you can enter a description for each record which then appears in the legend behind the actual label (in italics). I would be happy doing that if it weren’t such a pain to manually enter all these descriptions. Is there a shortcut to this ? I can’t seem to find it.

legendlabel

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