topic how generate missing contour lines from existing contour lines? in ArcGIS Spatial Analyst Questions

how generate missing contour lines from existing contour lines?

AliciaShyu_Love — Wed, 02 Sep 2015 22:54:57 GMT

I have some elevation data as contour lines but there are places where the contours just stop. I've been reading about interpolation but they all start with points, is there any interpolation method that I can do using the existing contour lines? Thanks!

Re: how generate missing contour lines from existing contour lines?

XanderBakker — Wed, 02 Sep 2015 23:14:46 GMT

You could interpolate the existing contours, using Topo to raster (Topo to Raster—Help | ArcGIS for Desktop , and then derive new contours, but you will loose precision.

Re: how generate missing contour lines from existing contour lines?

XanderBakker — Thu, 03 Sep 2015 11:40:57 GMT

If the incomplete contour lines cause undesired artifacts at the ends you could consider excluding them from the interpolation.

Question: how were these contour lines generated? It seems a little strange that every second line stops at a similar Y (lat) value.

Re: how generate missing contour lines from existing contour lines?

AliciaShyu_Love — Thu, 03 Sep 2015 18:46:23 GMT

The contour lines are USGS 24k. We need areas above 2500ft (middle pink line in image) but the 2500 contour is missing at certain areas. After reading about interpolation I was hoping that we could create a complete 2500 ft contour.

Re: how generate missing contour lines from existing contour lines?

DanPatterson_Retired — Thu, 03 Sep 2015 20:20:52 GMT

you can't produce a new contour or extend an existing without re-interpolating

Re: how generate missing contour lines from existing contour lines?

ChrisDonohue__GISP — Fri, 04 Sep 2015 04:10:45 GMT

I wonder if maybe a more complete contour data set is available, which would save having to interpolate. Here's some links that may be of help:

topotools.cr.usgs.gov/contour_data.php

Topographic Science

nationalmap.gov/viewer.html

The National Map: Viewer and Download Platform

Chris Donohue, GISP

Re: how generate missing contour lines from existing contour lines?

FrankKnorr — Fri, 04 Sep 2015 06:39:41 GMT

An other way with the extension 3D Analyst is:

1. Make a TIN with the contour lines. The contours are hard break lines in the TIN and every line must have an elevation.

2. From the TIN you can generate contour lines in several Intervalls.

Re: how generate missing contour lines from existing contour lines?

DanPatterson_Retired — Wed, 16 Sep 2015 02:05:28 GMT

resolved?

Re: how generate missing contour lines from existing contour lines?

AliciaShyu_Love — Wed, 16 Sep 2015 14:47:20 GMT

Sorry, got pulled to do another project. Haven't had a chance to do the interpolation for the contours yet.