Elevation interpolation along a (sewer) line

[TomSedlacek]

Hi smart GIS folks,

Here's what I want to do.  I have a vector sewer line feature class that contaings a field for the high invert elevation and one for the low invert elevation.  I can turn them into a raster no problem but what I can't figure out is how to interpolate between the two ends (high and low) and assign the elevations to the raster cells.

Ultimately what I need to do is compare the sewer line raster to an elevation raster to determine likely overflow points in the event of a backed up line.  My thought is it would be similar to creating a reservoir with a blockage being the dam.

I hope I articulated my question sufficently.

Any thought??

Thanks!

Tom S

[DarleneWilcox]

Hi Tom,

If you have the elevations at the endpoints you can create a TIN -- the elevations would be wildly inaccurate overall, but EXACTLY what you need between the points.  In short:

Create a TIN using your endpoint elevations (not knowing exactly how your data is organized you'll have to figure out how to assign the correct elevation to each endpoint).  Then, do a TIN to Raster, being sure to match the extent and cell size of your DEM.  This raster will be garbage everywhere except along the path of the sewer lines, where it will be perfect.

You can Polyline to Raster to get a raster version of the sewer lines, use that to extract just the along-the-sewer-lines values from the raster you created -- it will get rid of all the inaccurate elevation numbers everywhere else (that is, not along the sewer lines).

Hope this helps!  Cheers, Darlene