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Regular Contributor
Posts: 212
Registered: ‎11-16-2015

More Interpolating Points

Hi,

 

I'm trying to interpolate points using the create surface operator in spatial modeler. I'm having problems with polygons shaped like this:

 

2018-09-27 19_46_26-Untitled_1 - ERDAS IMAGINE 2018.png

 

I've created points around the edge and attributed them with height values. However, if I try to interpolate, it doesn't recognise that it's the inside of the polygon where I want to interpolate, it just takes the points that are closest to each other and interpolates between them. 

 

Is there a way I can tell it to interpolate within the polygon? Any other ideas how I can create a surface with polygons like that?

 

Cheers,

 

Johnnie

Staff
Posts: 576
Registered: ‎02-02-2016

Re: More Interpolating Points

Hi Johnnie,

 

Can you share your spatial model?

 

Thanks,

 

Stephen Bent

Hexagon Geospatial Support

Regular Contributor
Posts: 212
Registered: ‎11-16-2015

Re: More Interpolating Points

Sorry, got severely sidetracked. What I'd like to do, and what works for me, is to replicate the interpolation function on the Panchromatic tab, using only digitised points. I'm pretty sure the Surface operator in SM doesn't do that. Anthing that might? Cheers, Johnnie

Technical Evangelist
Posts: 698
Registered: ‎10-01-2015

Re: More Interpolating Points

Hi Johnnie,

 

I'm pretty sure the Convert to Surface operator will do what you are asking (if you give it points or lines). However it does use a TINing method, not the Distance Weight or Summation methods that are available in the raster editing tools. I think I mentioned in another discussion thread that if other interpolation methods are desired, please log an Idea for them.

 

If you're looking to constrain the areas that get interpolated, you might want to check out what was done in this Spatial Recipe:

 

http://community.hexagongeospatial.com/t5/Spatial-Modeler-Tutorials/Fill-Holes-in-a-DEM-by-Interpola...

 

In your original post you said that you couldn't get spatial modeler to interpolate in certain areas. There certainly is a distance threshold for the TIN method, but the areas you indicated worked looked larger than those indicated as failures, so it shouldn't be that. Were you Previewing rather than looking at an actual output file? When I tried it just now it looked like there might be some issues with previewing the results of Convert to Surface, but the file results looked correct. 

 

Cheers

 

Ian

Ian Anderson
Chief Product Owner, Desktop Remote Sensing
Hexagon Geospatial
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