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I am using ArcMap. I need to extract the intersection point of the cross section line (blue line) where it intersect with the height variation value of 5m in both sides of the section from the mid point(green point)of centre line represented by red line. Elevation values stored in DEM

enter image description here

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    Please update your image and indicate an example of the intersection point you want to find, it's not clear from your description what exactly you want to identify? – Hornbydd Apr 22 at 11:19
  • Could you reclassify your DEM to be a binary raster (i.e. +- red line center height = 1, everything else = 0), and then intersect your green lines with this binary raster? – ycartwhelen Apr 22 at 12:18
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    Your updated image makes no sense. Each contour line will be a different elevation so how can they be all tagged as 5m? – Hornbydd Apr 23 at 11:16
  • actually those are not elevation values . Those are height variation values from mid point of the cross section which intersect with centre line. I need to get boundary of the 5m depth valley (5m depth should be measured from either side of stream flow) – S.JP Apr 23 at 16:23
  • So are you saying if a green point was at elevation 100m then you are looking for elevation points along the blue line at 105m? The next green point might be at 119m then you are looking for the elevation 124m for left and right point along the blue line? – Hornbydd Apr 23 at 19:31
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He is a suggested workflow for you to follow:

  1. Make sure your blue lines and green points share a common ID value (integer) that links them
  2. Convert your line to raster based upon that ID, use the Polyline to Raster tool
  3. Extract from the DEM the cells under the raster line using Extract by Mask
  4. Identify the elevation under your green point for that line, you could use Get Cell Value tool
  5. Now use the CON tool to identify the pixel that is green point elevation + 5m, all others get set to nodata.
  6. Repeat for next line

Unless your base DEM is changing by units of exactly 1m then you might have to bracket the 5m value and maybe except 5m +/- 2m.

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  • Thank you for the answer. i need some further clarification, do i have to use the elveation raster file extracted based on the cross section line as a input conditional raster? – S.JP Apr 27 at 6:34
  • Yes that is correct. Using the masked out raster limits the cells to those under the line. – Hornbydd Apr 27 at 8:59

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