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.

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 !

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.

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.

GIS File Formats

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

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.

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.

Open Source GIS

While I’m still busy using and learning ESRI ArcGIS, I’m intrigued by the idea of using an open source product. In the long run, open source will run our lives. Compenies like Microsoft will eventually shrink to a sliver of market share, as first Google comes out with a future Android that ships on a CD and is guaranteed to install and run on any PC. And then Google – after finally creating the ultimate easy to install, totally free, open source OS – will loose market share as other will take over, once open source rules to market… my vision anyway. Mainly, I’m interested in open source GIS because ESRI products are so damn expensive if you’re just interested in teaching yourself some GIS skills and can’t get your company to take the plunge and buy the products.

Last year, after successfully installing and dabbling with Ubuntu Linux, I made several unsuccessful attempts to install PostGIS under Linux using instructions from GIS for Web Developers. My experience still haunts me. The books had looked promising. But nothing described in it seemed to work for me. After enjoying my time with Ubuntu, I went through all the stages of Linux-Abhorrence that have certainly been the cause for Linux meager market share. Confusion – Frustration – Anger – Fury – Hatred !

Ubuntu was easy to install and works great. 50% of computer users would do just fine using only Ubuntu installed straight from the CD. But getting any program beyond the basic installation package to run, was a pain. I understand the process. Getting and installing packages, etc. Blablabla. But there was always some stupid library file missing. I kept un-installing, upgrading, re-installing… jumping through hoops in circles, and never got anything to work. If Ubuntu (or any other Linux for that matter) is ever supposed to for me as the only OS, it’s ging to take someone like Google to make Android Linux work as “smoothly” as Windows (cant believe I just said that.

Anyway, back to open source GIS. PostGIS went R.I.P. on me. Now, I’ve downloaded GrassGIS and installed it under Windows. So far, it looks pretty cool. I’m eager to see how this compares to ArcGIS. Here is a free manual to get me started. Open Source GIS: A GRASS GIS Approach on amazon.com got rave reviews, too, and looks promising.

PS: Interesting thoughts on Open Source GIS by Bill Dollins on his cool blog.

ArcGIS Spatial Analyst and ModelBuilder

I finally upgraded to ArcGIS 9.3 and renewed our maintenance agreement to stay on top of future upgrades. I also installed a 60-day trial of Spatial Analyst because I came across a useful little tutorial for Model Builder and Python which required the install. The whole Model Builder environment seems straight forward although after what little programming I have now done, I think I would prefer “writing code” over plotting and connecting a bunch of little balls and boxes. So this might turn into some kind of reverse engineering where you “box ‘n ball” a template and then go back to tweak and tune things in Python using the script. But I haven’t gotten there yet. I should pace myself.

GIS Data for Project Maps

I have been creating lots of site vicinity and geologic maps for geotechnical investigation using ArcGIS lately. Working around the Dallas-Fort Worth metroplex, I used to rely on GIS data provided by the North Central Texas Council of Governments (NCTCOG) – an awesome resource for this area. But once you leave the counties that are part of NCTCOG, you have to either use ESRI data or find another source, e.g. TNRIS (Texas Natural Resources Information System). I’ve been especially pleased with the digital version of the Geologic Atlas of Texas, or GAT,  (supplied by TNRIS).

One problem I’ve run into is that the ESRI data that comes with ArcGIS doesn’t seem to include many of the smaller bodies of water in Texas, e.g. most smaller lakes. However, the GAT files have all these maps in the. I’ve been extracting the lakes from the geology shapefiles and adding them as a new layer to my vicinity maps with missing lakes. However, I find that bodies of water mapped by GAT overlap very inconveniently with roads and other features in the ESRI data ! What to do ? Turns out that the US Geological Survey provides National Hydrography Dataset (NHD) information. Here, you select a geographic area and the hydrologic features you’re interested in, e.g. water bodies, and have the information emailed to you as shapefiles. On my most recent map, the outline of the lake I needed fits in perfectly with the highways and streets shapefiles from ESRI.