topic Re: Creating a TIN from DEM: Using a TIN to analyze lineaments in 3D Questions

Creating a TIN from DEM: Using a TIN to analyze lineaments

RoslynWoods — Thu, 10 Oct 2013 23:03:02 GMT

I have been trying to figure out a way to analyze lineaments for my senior thesis.

I am using ArcMap 10.1 and have a 60m DEM of my study area.

For simplification of my project, I basically want to use the DEM to extract breaklines, or lineaments, that may represent faults and zones of weakness in the topography, basically just lines.

I first looked into doing a normal slope/aspect tool on the DEM,and then got stuck on actually creating the lines and extracting them, but then my advisor redirected me and suggested using TINs.

I don't know much about using this type of processing, but I used the tool "Raster to TIN" and tried to use TINLine to extract lines in the data. But nothing happened. No lines appeared in the product.

I'm asking if there is a step that I have to complete to make these other tools work. Like my DEM did not fully turn into a TIN? and "Create TIN" does not accept the "Raster to TIN" product. How do you actually create a TIN so enable processing to work?

Any help would be appreciated.

Also, on a side note, if anyone out there knows how to possibly extract lines from a slope/aspect tool that would be helpful as well.

Just exploring my options.

Thank you.

Re: Creating a TIN from DEM: Using a TIN to analyze lineaments

NeilAyres — Fri, 11 Oct 2013 06:57:04 GMT

I would stay with rasters and spatial analyst.
But extracting geological features automatically from a dem might be quite tricky.
But you must explore the various filters and other surface operators to enhance abrupt changes of slope.
sa.Curvature might be one example. There are high and low pass filters in there as well.
But again, sorting out which feature is a "lineament" from say a stream line, will be a challenge.
If you want a good book on analyzing this sort of stuff my bible is :
"The Image Processing Handbook" by John C. Russ. Highly recommended.

Good luck,
Neil

Re: Creating a TIN from DEM: Using a TIN to analyze lineaments

TimBarnes — Tue, 15 Oct 2013 02:02:31 GMT

Hi Sophie- You kind of have your process backwards

In a TIN, break lines are a feature all in themselves, the TINLines tool doesn't know about abrupt changes in the topography (i.e. faultlines) as such, it just extracts the existing break lines into a new feature class.

With a raster DEM, no such information about breaklines exists and converting a raster DEM to a TIN won't automatically add breaklines since everything is simply coded as pixels of different values. Extracting them therefore becomes a task in actually analysing the terrain to extract the changes in topography that you are interested in.