topic Re: Identifying Trenches using DSM/DTM in ArcGIS Spatial Analyst Questions

Identifying Trenches using DSM/DTM

HazelAng1 — Sat, 01 Apr 2017 11:54:14 GMT

Hi all,

I'm trying to do a study using GIS and I need to identify trenches more than a certain width. I have a raster elevation layer and all I can think about is to first do a flow analysis to identify the flow path as it is where the trenches are likely to be at. However, I am not too sure on how I can get the width of these areas. Anyone has any ideas?

Thanks!

Re: Identifying Trenches using DSM/DTM

DanPatterson_Retired — Sat, 01 Apr 2017 13:41:49 GMT

My first thought... what is the raster cell size? If the trench is only a couple of meters wide and your cell size is similar, then the chance of estimating the trench width is pretty slim. So how wide are the trenches and how big are your cells, and are they relatively flat bottomed with steep sides? If the trenches are wide and deep with respect to the cell size, you might want to consider identifying areas with rapid changes in slope and/or curvature. If these features (linear in nature) can be identified, you could use Euclidean distance perhaps to estimate trench width from it.

Having said this... an image showing your study area would go a long way

Re: Identifying Trenches using DSM/DTM

HazelAng1 — Sun, 02 Apr 2017 05:05:01 GMT

Hi, the raster size is sub meter and I'm looking at trenches of more than 5m.

I will try to use the method you suggested (slope/culture) and see how it goes. Thanks for your help!