shrug-l: DEM and TIN

Andrew C. Rudin ACRudin at lan-inc.com
Fri Jan 20 13:52:47 EST 2006


Question 1.
 
If you know VBA, you can pull Z values from positions along the Line.
For an example, check out the ET Geowizards Easy Calculate function
Polyline_Get_Z_Midpoint.  You'lld have to modify that one to pull z
values at set distances along the line and export them to a dbf or txt
file.  Then bring these into excel for manipulation.
 
Question 2.
 
I did something similar for Jon Arthur on the SWFWMD project.  One point
data set was more acurate than the others.  What I did was create a
raster surface for both data sets.  I then created a gradiated buffer
around the more acurate points. When a cell is not in the buffer, only
the value from the less accurate data is used.  When a cell is in the
buffer, an average of both data sets is used.  Since the buffer is
gradiated, the closer you get to the accurate feature, the higher the
percentage of the accurate data value is used.  All done with raster
calculator.  It ended up making mound features around the accurate
points, I believe making the buffer gradient a bezier curve helped.
Just takes some playing to make it look like what you want.
 
Andrew Rudin, GIS Analyst 
Lockwood, Andrews & Newnam, Inc. 
10801 North Mo-Pac Expressway 
Braker Pointe, Building 1, Suite 120 
Austin, Texas 78759 
Telephone: (512) 338-4212, ext. 52 
FAX: (512) 338-4942 
Email: acrudin at lan-inc.com 


  _____  

From: shrug-l-bounces at lists.dep.state.fl.us
[mailto:shrug-l-bounces at lists.dep.state.fl.us] On Behalf Of Thomas, Jim
Sent: Wednesday, January 18, 2006 3:55 PM
To: SHRUG
Subject: shrug-l: DEM and TIN


All,
 
I have two questions.
 
1.  Is there a way to export profile information from 3D Analyst to
Excel?  I can get a profile drawing in a window, but it's useless.  I
would like to export the profile data, so I can have more control over
the input/output.  I'm using the NED and NHD.
 
2.  Can you combine raster and vector data to create a new TIN?  I have
some good surveyed elevation data that I want to merge with not-so-good
DEM elevation data to create a continuous surface representing the best
data available.  Example:  The survey data includes road centerlines,
edge of water, and some spot elevations, but nothing in between.  I want
to use the DEM to fill in the gaps.  Is this even possible or
recommended?
 
Thanks.
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