topic Re: how to half contours distance PLEASE HELP. in 3D Questions

how to half contours distance PLEASE HELP.

lyndonriddle — Thu, 13 Mar 2014 09:25:55 GMT

hay every one

I have a map with contours of 2m.

I would like to know if I can convert this into 1m or other contour distances..
If i can, Please advice me how.

Thank you

Re: how to half contours distance PLEASE HELP.

lyndonriddle — Thu, 13 Mar 2014 15:42:52 GMT

HELP PLEASE.

Re: how to half contours distance PLEASE HELP.

BondHarper — Thu, 13 Mar 2014 15:48:46 GMT

Do you have a TIN, DEM, or Terrain for the area? Your best bet would be to create contours using either Contour or Surface Contour from one of these datasets. Depending on where you need the data for, there are a lot of sources (global USGS, government, or even purchase from private vendors). It is possible to create a TIN from your contours and then re-generate 1m contours, but they would not accurately represent the true ground surface so I would not recommend it.

Re: how to half contours distance PLEASE HELP.

lyndonriddle — Fri, 14 Mar 2014 09:10:36 GMT

Do you have a TIN, DEM, or Terrain for the area? Your best bet would be to create contours using either Contour or Surface Contour from one of these datasets. Depending on where you need the data for, there are a lot of sources (global USGS, government, or even purchase from private vendors). It is possible to create a TIN from your contours and then re-generate 1m contours, but they would not accurately represent the true ground surface so I would not recommend it.

I have the contours file in .dbf .prj .sbn .sbx .shp .shx

It does not have to accurate.

Sorry i am not very good with GIS. I am student that has self tough himself to use it and not to sure how to do this.

Thank you

Re: how to half contours distance PLEASE HELP.

808707 — Fri, 14 Mar 2014 14:24:08 GMT

How about convert Contours to Points. Use the point elevations to create a TIN. Convert TIN to DEM. Using DEM to create new contours.

Re: how to half contours distance PLEASE HELP.

RobertBorchert — Fri, 14 Mar 2014 14:29:15 GMT

What area are you looking in? Perhaps it would be be to try and find better contours

I know in my region we have 2 foot contours available.

I have the contours file in .dbf .prj .sbn .sbx .shp .shx

It does not have to accurate.

Sorry i am not very good with GIS. I am student that has self tough himself to use it and not to sure how to do this.

Thank you

Re: how to half contours distance PLEASE HELP.

lyndonriddle — Fri, 28 Mar 2014 11:41:42 GMT

What area are you looking in? Perhaps it would be be to try and find better contours

I know in my region we have 2 foot contours available.

I am looking at the entire KwaZulu Natal cost line in South Africa.

I am really battling.

Nothing is working.

I am not that good at GIS which does not help

Re: how to half contours distance PLEASE HELP.

ShaunWalbridge — Fri, 28 Mar 2014 16:24:22 GMT

Most of the tools for creating contours assume you have an elevation dataset, like a raster or a TIN, which the contour lines can be derived from. It is possible to interpolate between the existing contours you have, but fairly tricky to do. The approach Mark mentions above is probably your best bet. Right now, you have contours which are at different heights, so each line contains the height (or depth) of the values along it. If you convert those lines into points, you can interpolate a surface, and make a "fake" DEM which includes the data that you do have (from the contours). Then, you can use that new raster DEM to create contours at the resolution of your choosing. Note that these will be interpolated, and may not be accurate.

So, taking your contours, this would look something like:

Data Management Tools > Features > Feature Vertices to Points

Spatial Analyst Tools > Interpolation > IDW (there are many other approaches to interpolation, IDW is perhaps the simplest).

Spatial Analyst Tools > Surface > Contour

cheers,
Shaun

Re: how to half contours distance PLEASE HELP.

SteveLynch — Tue, 01 Apr 2014 11:51:57 GMT

When creating a DEM from contours one should rather use the TopoToRaster tool. It is designed for that purpose.

When converting lines to points and then interpolating the points you'll often get terraces in the output DEM and that is why a more suited tool should rather be used.

-Steve