Network Analyst and Geoprocessing in the Background

Well, I never used wordpress, oh well. Anyway, I realized as much as I like twitter and such, I still need to blog for my own documentation of ideas and GIS techniques.

So here it goes, again:

So the last day or two I've been running in to this problem with using Network Analyst for geoprocessing. It seems that running it in the background in ArcCatalog doesn't work but running in the foreground in ArcMap works fine (I'm running 10.0 SP5-maybe 10.1 fixes this).

I've avoided scripting Network Analyst functions for a while now but decided to make the leap. So after much frustration and reading the Esri forums (which are still annoying since the migration), I found out it will only run in the foreground. I'm getting some weird server error. So no big deal, just sort of a crummy workaround.

Removing or Flattening Z and M values from a point Feature Class

I've had to flatten a Z value-laden point file before, or for whatever reason seen CAD data with M-awareness. For the life of me though I couldn't recall how the heck I did it in the past. It's like those tasks in GIS you do only once in a blue moon and cannot remember the name of the tool or what terms to search (see lattice dem).

Anyway, its actually a very simple process of exporting your data in ArcCatalog and just setting the environments.

http://support.esri.com/en/knowledgebase/techarticles/detail/35818

from Esri:

Summary

Instructions provided describe how to create a copy of a feature class and disable M- and Z-value associations for the output feature class. These associations cannot be removed from an existing feature class.

M-values are routing values.

Z-values are elevation values.

Procedure

1. Browse to ArcToolbox > Conversion Tools > To Geodatabase.
2. Open the Feature Class to Geodatabase (multiple) tool.
3. Add all the feature classes into the Input Feature Class parameter.
4. Select an Output Geodatabase.
5. Click the Environments button at the bottom of the tool dialog box.
6. Expand the General Settings.
7. For the parameter, Output has Z Values, change the value to Disabled.
8. For the parameter, Output has M Values, change the value to Disabled.
9. Click OK in the Environments dialog box.
10. Click OK to execute the geoprocessing tool.

Esri Press Books I've been reading & Float vs Double

It's been a while since my last post, I've been using twitter more and more, which means I've been posting less and less content and tips and tricks. I've been spending a lot of time messing around with Python (and after a few months of realizing I had the wrong installation of Python, I've now got my arcpy and other modules running smoothly) and relearning how to do things with modelbuilder.

I've started going through Getting to Know ArcGIS: Modelbuilder (http://esripress.esri.com/display/index.cfm?fuseaction=display&websiteID=195&moduleID=0) to help relearn and understand the things I've been doing for a few years. This is the first comprehensive text on modelbuilder I've seen and there is so much value in Iteration and a whole slew of other tools that would have helped my modelbuilder experiences earlier on.

I've also been reading Modeling Our World (2nd Edition): The ESRI Guide to Geodatabase Concepts (http://store.esri.com/esri/showdetl.cfm?SID=2&Product_ID=1247&Category_ID=56). This book is really great. It provides a great overview of GIS data and is a great all-in-one refresher. So I'm going to try and post more and more about the little things in ArcGIS.

Now, on to Float vs. Double.

So for a long time I've been defaulting to using Double because it allows for 16 significant digits. However, as I read in Modeling Our World, Float stores 7 significant digits and is half the storage space of Double. I usually use Double when dealing with decimals but after realizing that I'm essentially expanding all my databases, with sometimes many many fields, to be double (no pun intended) the size they need to be because often when I deal with decimals, 7 digits is more than enough. So by cutting down the size of my databases I will be reducing my storage footprint but also hopefully speeding up my processing time.

DUHHHHH.

So the takeaway should be, if you don't need Double, use Float.

"Floats use half the byte storage of doubles" - Michael Zeller, Modeling Our World

For more info on field types see:
http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//003n0000001m000000.htm