topic Re: Divide a raster even sections in Data Management Questions

Divide a raster even sections

RichardSullivan — Tue, 09 Nov 2010 14:15:22 GMT

I have Lidar coverage over a large section of a beach. I would like to break that raster into separate sections 100m wide. I would then like to color code those sections based on whether a certain elevation exists in the swath. I can do this manually, extract by mask one section at a time, but is there a more automated way to do this? Say... by dividing a raster into multiple sections based on a polygon or something?

Any ideas?

Re: Divide a raster even sections

RobertBerger — Tue, 09 Nov 2010 14:26:13 GMT

Hi Richard,

At ArcGIS 10 there is a tool for splitting up your raster, called split raster. This should do the trick for you.
Alternately, there is also sample code online if you want to do something similar through code (e.g. at 9.3).
Hope this helps.

Robert

Re: Divide a raster even sections

RichardSullivan — Tue, 09 Nov 2010 15:52:25 GMT

Hi Robert,

I just started using Arc 10. Thanks for the advice. However, I'm having difficulties getting a usable output from the tool. The strip of land I would like to segment is ~77km long. I want tiles that run the length of the land North and South, but are only 100m East to West.

I was unable to get the tool to work by specifying the size of the tiles. I did make some headway with number of tiles. I'll need about 770 tiles, but the tool only outputs 10 before it begins insisting that the other tiles already exist, "Failed to create 2004_10', it may already exist". The ten it does output are exactly what I need though... it's just 760 too few.

Any thoughts?

Thanks,
Richard

Re: Divide a raster even sections

RichardSullivan — Tue, 09 Nov 2010 16:23:59 GMT

Nope... never mind. Figured out the issue.

The raster I was splitting actually had a 12 character File name (Location and Year). The tool wants to append a number at the end of the original Raster name to mark each segment. 0-9 made the filename 13 characters long. When I hit the 11th segment, the filename became 14 characters long and it all fell apart.

It's scary how often the filename length is an issue.

But once I made that realization, it all worked wonderfully.

Re: Divide a raster even sections

RobertBerger — Tue, 09 Nov 2010 21:16:30 GMT

Richard,

Is there a reason you output to GRID? If you use grid because of spatial analyst, then did you realize that spatial analyst can also output to TIFF etc. without conversion at ArcGIS 10?

Robert

Re: Divide a raster even sections

JenniPelc — Tue, 04 Jan 2011 23:04:25 GMT

I've been trying to use the split raster tool and I am gettin no output, but am getting no error messages. Everything indicates the tool is running properly. I've checked the filename length...any thoughts?

Re: Divide a raster even sections

RobertBerger — Thu, 06 Jan 2011 14:39:25 GMT

Greetings,

What format are you outputting to? In general I would suggest using common formats that can hold just about any bit depth such as TIFF or IMG. GRID is also ok if you consider the length and other limitations.

Robert