topic Re: Surface Analysis missing contours in ArcGIS Spatial Analyst Questions

Surface Analysis missing contours

WesKing — Thu, 10 Jun 2010 17:21:16 GMT

9.3.1 Service Pack 1. Raster Information is...GRID, columns and rows = 31353, 31996, Cellsize = 0.3048, 0.3048, Uncompressed Size = 3.74 GB
Attempting to create 1 foot contour intervals using Z factor: 3.28083 (meters to feet). The contour shapefile created has missing contours. Not only are there certain areas where contours are not created, but in these areas contours are broken and not complete (see attached). With Z factor the minimum contour is 2271 and max is 3182 (total of 912 contour values).

I have tried using the Contour tool and the Contour with Barrier tool (using no barrier). I have tried with a grid and .img. I have tried with and without using focal statistics. The only way I can create contours in this missing areas is by creating a mask for that specific area and running tools on that area. This will be too problematic for the large number of areas I will be working on.

Can someone help with this please?

Thanks,
Wes

Re: Surface Analysis missing contours

SteveLynch — Thu, 10 Jun 2010 20:20:44 GMT

Wes

Please run your input raster through the IsNull tool. If the output has only 0's, then please convert the contours input to raster .img, zip it and email it to me at slynch@esri.com

Thanks
Steve Lynch
ESRI

Re: Surface Analysis missing contours

WesKing — Thu, 10 Jun 2010 22:00:47 GMT

Steve,
Thanks for the reply. IsNull resulted in all 0's as expected. However, I was just running another trial and found that it worked if I ran things slightly differently. 'Value' are in meters, but I was using the z factor to result in 'Value' of feet, at 1 foot intervals. This time I ran Contour with a contour interval of .3048 and no z factor. This adds another process to the overall process, but I think I can deal with that.

I would like to be able to send you the .img but that's a no-no where I work. If I can work it it will send it, but I doubt it will happen.

For now I'd like to just take the input raster (float type and Value in meters) and convert the Values to their corresponding elevations in feet before running Contour. I'm running my first trial and am using Raster Calculator, which is pretty quick and painless, but is there a better way to do this raster Value conversion?

Thanks again,
Wes

Re: Surface Analysis missing contours

SteveLynch — Fri, 11 Jun 2010 17:12:36 GMT

Wes

Use the Times tool

Steve

Re: Surface Analysis missing contours

WesKing — Tue, 15 Jun 2010 18:47:54 GMT

Wes

Use the Times tool

Steve

Thanks, worked great