samfranklinUK

Convert depth raster to polygons of 10m intervals

Discussion created by samfranklinUK on Mar 9, 2011
Latest reply on Oct 9, 2013 by sarah_goode
Using: ArcGIS (ArcView) 10. Have extensions 3DA, SA and xtoolsPro.

Hi

I have a asc file representing a depth grid. I have an area within this grid that I want to generate a polygon feature class that represents depth grouped into 10m depth ranges.  I'll can then symbolise this based on the 10m range classification and importantly undertaken spatial analysis on the polygons with other feature classes. Essentially certain depth ranges represent constraints for my exercise.

I can get close to achieving the desired polygon feature class, via two methods, but both seem massively convoluted. Is there a better way?

Option 1: via xtoolsPro & SA:
1. convert asc to raster (using conversion toolbox)
2. generate contours at 10m intervals (using SA toolbox)
3. generate a polygon of the extent of a raster (I had this previously, my client's licence area)
4. Split extent polygon by polylines (using xtoolspro) = this gives closed polygons of depth areas at 10m intervals BUT the polygons have no attributes are carried through using xtoolsPro.
5. then I was going to somehow query the polygons and calculate field to populating a depth range.
could do this manually or via python maybe?

Option 2: via SA only.
1. convert asc to raster (using conversion toolbox)
2. generate a Integer raster from the original float raster (using map algebra tool in SA toolbox)
3. Convert integer raster to polygon (using conversion toolbox)
4. create a new field called 'depth range' in the polygon layer attribute table
5. query by attribute and calculate field, and populate the depth range field for each individual polygon that represents each pixel.
6. merge features based on there depth range.

I can script in python (still learning!), which could help with automating the calculate field operations but thought there must be a better way of doing this?

Also, I checked out creating a TIN from the raster, but couldn't see an easy way to extract polygons based on ranges of values (I didn't understand TIN tags by the way).

Please help? Hope this is clear.
Cheers - Sam

Outcomes