2

I have a raster converted from shapefile (tool point to raster). Can anybody prompt, how to display coastline?

I can use contours, but are not focused at condition "elevation = 0". Is there any simple way?

screen

Colors

colors

10
  • How, exactly, do the colors you display represent values in the raster?
    – whuber
    May 19, 2015 at 20:48
  • @whuber I set this classified scheme myself. Added description to question
    – lenden
    May 19, 2015 at 20:51
  • Does that legend imply the coastline should be found at all zero values? Although it would seem to, that appears to contradict your statement about the zero elevation contour. How do you reconcile that?
    – whuber
    May 19, 2015 at 20:52
  • @whuber I don't mean, that coast line is absolutely "elevation = 0". I wanted to say, that contours are not focused at "elevation is about 0", implying coastline. Really I don't think, that "=0" is possible, obviously there are different changes of elevation, some where neighbours can have 1 and -1, somewhere 10 and -1 and so on
    – lenden
    May 19, 2015 at 21:09
  • 1
    How about Contour List resources.arcgis.com/en/help/main/10.1/index.html#//…? with only one entry in the contour values (0) that will give you the coastline from the DEM for that vertical datum and not fully contour the entire raster at an interval. May 20, 2015 at 2:40

1 Answer 1

1

If you specifically want a single elevation (or specific elevations) as lines you can use Contour List (3d analyst, Spatial analyst). Unlike Contour (3d analyst, Spatial analyst) which creates contours at a specific interval the contour list tool produces contour isolines at specific elevation values.. for this example you would supply the value 0 for contour_values:

enter image description here

Note that both of these tools require either of 3d analyst or Spatial analyst extension for ArcGis. If you don't have access to either of these extensions (or ArcGis) you can use GDAL_Contour to extract the coastline by supplying a ridiculously high interval:

gdal_contour -a elev dem.tif contour.shp -i 2147483647.0

2147483647.0 is the maximum value for an INT32 - 32bit integer, substitute a value greater than either the maximum value of the raster or the absolute value of the minimum and only the 0 contour will be produced. A specific value can be obtained using -off value but the contour will be given elevation of 0.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.