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Why doesn't Create Fishnet work with Opposite Corners?

December 16 2009 | 2 comments
Categories: Map Data

I'm trying to create a regular grid on a map. Create Fishnet seems to be the easiest way. The wrinkle is that the grid is tilted -- nor oriented NS-EW. If I just start entering "Origin" and "Y-axis" values, the "Opposite Corner" boxes are greyed out.

Help says that, "If 0 is specified for the Cell Size Width and the Cell Size Height, then specify the number of Rows and Columns, and the opposite corner of the fishnet (X, Y)". If I put 0 in for "Width" and "Height", the "Opposite Corner" box is now active. However, when I run this tool with 0 in for Width and Height, it complains that you have to have a non-zero width and height.

The command line syntax for what it complains about is as follows:
CreateFishnet Caveman_Fishnet "423911.767 1305126.632" "423966.262 1305159.753" 0 0 27 74 "424066.769 1305003.038" LABELS # Caveman_Fishnet_label

What gives?

Mapping Center Answer:

In scripting and command line, the arguments must be passed as strings. So the correct arguments will be: "0" "0" "27" "74" for cell size and rows/cols. We ran the tool (from dialog) with the same parameters and the tool ran successfully.

Also, I notice that your Y coordinate for the opposite extent of the Fishnet is less than the Y coordinate for the origin -- this means that you will be making a fishnet with the origin in the upper right corner and the cells will be created southeast of that location.  There is no restriction on which direction you create the fishnet in, but I just wanted to make sure you understood how you will be creating the fishnet cells.

Documentation about the opposite corner values posted by Aileen Buckley on Jan 11 2010 10:26AM
Y-axis coordinate and origin are used to set the inclination (orientation but not the direction). Origin does not move – it’s like an anchor point. We have updated our doc about the way orientation is set by the tool so you will find this in the next release. The opposite corner is used to set the overall size and position of the fishnet – the resulting opposite corner may not be the one the user sets as it's recalculated based on other parameter values.
Command line posted by Aileen Buckley on Jan 11 2010 10:27AM
For command line: If you have not set the workspace before executing the command you're using, then you need to use the full path of output.

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