August 2, 2013
Testing for nulls in an Attribute Table

I always forget how to deal with nulls - must I treat it as a string or use the IS statement, then how do I need to reference the null value?  Is it case sensitive?

I found this post in the technical reports on the ESRI support website.  It is nothing new, but a nice quick reference on how to check for null values in my attribute table.  I’m using 10.1 and didn’t have to specify to use a Arc 9.3 Python parser (but then again, that may be the default…)  Anyway, it is a super simple definition to put into a Python Codeblock:

def IsMyValueNull(field):
    if field is None:
        return UpdatedValue
    else:
        return field
IsMyValueNull(!myField!)

July 11, 2013
The past few days, I’ve had my nose buried in the new Animal Crossing installment on the Nintendo 3DS.  I’ve been a fan of the game since it was released on the GameCube and have always loved the task of creating a “perfect” town.  This is a game feature that calculates the synergy between the distribution of trees and flowers, and now public works.  It is always a difficult task; I find it much easier with a detailed map of my town.  This allows me to easily see the spatial distribution of trees, identify areas that are too dense or too sparse.  In the past, I’ve always sketched my town onto graph paper because it suits the gridded structure of the game.  However, sketching the map makes it difficult to update as I modify my town’s layout to create the ‘perfect’ rating.  This time, I chose to create the map in excel, a rather strange venue for cartographic production.  It was perfect for automatically calculating the number of trees in my town and updating it as villagers move in and out.  Though Excel still caused some issues since I wasn’t able to incorporate any angles into the map, and I’ve experienced some strange “null” spaces in the map where the cliffs and rivers bend and curve.
It was a fun little experience to create a map in Excel, something I’ve never done before.  For all we complain about ArcGIS, creating a map in this manner really teaches us how much Arc has improved the way in which we make our maps.

The past few days, I’ve had my nose buried in the new Animal Crossing installment on the Nintendo 3DS.  I’ve been a fan of the game since it was released on the GameCube and have always loved the task of creating a “perfect” town.  This is a game feature that calculates the synergy between the distribution of trees and flowers, and now public works.  It is always a difficult task; I find it much easier with a detailed map of my town.  This allows me to easily see the spatial distribution of trees, identify areas that are too dense or too sparse.  In the past, I’ve always sketched my town onto graph paper because it suits the gridded structure of the game.  However, sketching the map makes it difficult to update as I modify my town’s layout to create the ‘perfect’ rating.  This time, I chose to create the map in excel, a rather strange venue for cartographic production.  It was perfect for automatically calculating the number of trees in my town and updating it as villagers move in and out.  Though Excel still caused some issues since I wasn’t able to incorporate any angles into the map, and I’ve experienced some strange “null” spaces in the map where the cliffs and rivers bend and curve.

It was a fun little experience to create a map in Excel, something I’ve never done before.  For all we complain about ArcGIS, creating a map in this manner really teaches us how much Arc has improved the way in which we make our maps.

July 10, 2013
Help, Help! My Color Selector Palette Is Gone!

I just tried to change the color of a layer in my ArcMap session and my color selector palette has gotten corrupt; all of the default color swatches had disappeared and were replaced with many “odd” colors. After a moment’s panic, it was rather clear where all of the bogus colors had come from – my recent overuse of the eye dropper tool. The eye dropper tool in ArcMap can be a very useful feature for many reasons. I’ve been using it to test the apparent RGB colors on some transparent layers (attempting to avoid the known issue of flattening PDF exports when transparency is applied while raster layers are also in the data frame).

image

If you don’t use the eye dropper tool or didn’t know about it, it can be accessed in Customize Menu > Customize Mode. Click on the Commands tab. I find it easiest to type “eye dropper” into the search box (who wants to sift through all those commands?!?), but it is located in the Page Layout Category on the left. The Eye Dropper tool can then be found in the “abbreviated” commands list on the right. The tool can then be drug into any of the existing toolbars. I’m hoping that ESRI will at some point allow the user to create a custom toolbar, just like creating a style file… maybe this already exists somehow?

So, I’ve lost the convenient, yet limited color palate that ESRI has given me and I want it back, darn it! What happened in this case was that the eye dropper doesn’t just spit out the RGB values for the location you clicked, but saves it into ArcMap’s memory, which is why the color palette doesn’t reset when you close out and open a new map document. It may seem like the color swatches are lost forever, but the solution is much easier than you think. If ArcMap can remember these strange color swatches, they must be saved somewhere. In fact, they have been written to a style file. The solution to getting the default color palette back is to simply delete this style file but be warned, this will delete all of the color swatches that were just created.

The style file that must be deleted is located in the following directory:
C:\Users\[computer username]\AppData\Roaming\ESRI\Desktop10.1\ArcMap

With all ArcGIS applications closed, delete the [computer username].style file. It will be recreated next time you open ArcMap, with all of its default settings.

So, if you really needed one of those color swatches, my recommendation is to create a custom, project-specific style file. You can save some of the color swatches to this style file before you recreate the default one. Then, you can add and remove this style file from your map document at will… ahh, freedom!

June 26, 2013
This is a sample of some testing I’ve done to assess the shaded relief output after different strategies of generalization.  In a ladder based generalization, the data is first generalized to an intermediate scale before being generalized again to a target scale or final product (i.e. iterative filtering).  Star generalization is when the source data is generalized to be used directly at the target scale (i.e. resampling).The left 5 tiles represent a 10m DEM of the Grand Canyon area that was iteratively filtered using a low pass filter (ladder based generalization).  The right 5 tiles represent the original 10m DEM that was resampled to a 30m DEM (star) and filtered (ladder).  The results are then displayed at various scales to assess which is the best product.

This is a sample of some testing I’ve done to assess the shaded relief output after different strategies of generalization.  In a ladder based generalization, the data is first generalized to an intermediate scale before being generalized again to a target scale or final product (i.e. iterative filtering).  Star generalization is when the source data is generalized to be used directly at the target scale (i.e. resampling).

The left 5 tiles represent a 10m DEM of the Grand Canyon area that was iteratively filtered using a low pass filter (ladder based generalization).  The right 5 tiles represent the original 10m DEM that was resampled to a 30m DEM (star) and filtered (ladder).  The results are then displayed at various scales to assess which is the best product.

June 26, 2013
ArcMap Tips and Tricks

For those who crave the multi-tasking.  I know I learned a few things from this short document (which may or may not have been introduced a few versions ago)

  
Filed under: ArcMap Help Tips and Tricks