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creating 3d points from contours

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#1
gvlisnas

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Hi to all,

I have this problem. Lets say i have an area full of contours. I want to create points with a distance of 3cm of eachother in scale, that have the x, y and z value associated with the contours. I know i have to create a tin or a grid file. But don't know where to go from there.

I'm using arcgis 9.2

Thanks in advance!

#2
Hans van der Maarel

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Not an arc user myself, but the general steps would be:
- Generate a terrain model (TIN) from the contours
- Generate the grid with the spacing you require
- Drape the grid over the TIN
Hans van der Maarel - Cartotalk Editor
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#3
gvlisnas

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Yeah that would be the answer.

But does anyone know how to create the grid and especially generate the points?

#4
Aris

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Yeah that would be the answer.

But does anyone know how to create the grid and especially generate the points?


Hy

If you have spatial analyst tools you can use topo to raster (under interpolation) and define the output cell size. And then use the extraction toolset to make the file you want.

#5
gregory

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One of free tools from ET Geo Wizards which you can find http://www.ian-ko.com/ will let you to create point grid ( Create Point Grid).

Info about how to create TIN in Arcgis (3D Analyst requied):
http://webhelp.esri....reation_toolset

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Gregory

#6
frax

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I am actually not sure i would call this a tough problem. maybe that you are not familiar with the process, so that it is tough for you!

You should just break down the process into the steps required, and look at the available documentation for those. All of this functionality is built into ArcGIS and 3D Analyst and Spatial Analyst.

Good luck!
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#7
Charlie Frye

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I think you're looking for the Interpolate Shape tool in the 3D Analyst. You can use 2D point, line, or polygon inputs with a TIN or surface GRID.

To save yourself time in the future, the Online help has all of this and using the contents tab you could have followed Extensions: 3D Analyst: 3D Features: and then either creating or converting...

I know navigating the help isn't that easy for everything (or I wouldn't have a job doing Mapping Center), but for the majority of tasks finding something useful shouldn't take more than a few minutes.

Also, if you're looking to just generate random points within a study area (or a random sample of point features or vertexes from line or polygon features), we're adding that feature to the geoprocessor with the 9.3 release. This would be the sort of thing you would base an RMSE calculation on.
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#8
gvlisnas

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Thank you all for your help!

Actually it wasn't that tough but i was coming to a dead end.
I'm going with 2 solutions.
1. Creating a tin and then using Hawths tools generating regular points in a grid, and then adding the elevation info from the tin. Clipping the points using the area i want and done.
2 Generating a raster using topo to raster and then raster to features to create the points.

p.s. charlie arcgis 9.2 has generate random points. Maybe generating regular points should be added also.

#9
Charlie Frye

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p.s. charlie arcgis 9.2 has generate random points. Maybe generating regular points should be added also.


First, there will be more at 9.3 for random points, and to create regular points, there's a trick that's worth knowing:

In a geodatabase, create a fishnet grid (or use one of the grid generation tools on ArcScripts), then create a geometric network from that grid (you may need to convert polygons to lines first), and that geometric network will contain a point dataset for the juctions that will be in a regular point grid. Just make a copy of that feature class and delete the geometric network.
Charlie Frye
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