|
|
| GeoCommunity Mailing List |
| |
| Mailing List Archives |
| Subject: | RE: [gislist] GIS Survey Question |
| Date: |
01/26/2004 11:15:01 AM |
| From: |
Andrew Hunter |
|
|
This is a multi-part message in MIME format.
--Boundary_(ID_11nAFM2frLtiuFOo3Q+dBQ)
Content-type: text/plain: charset=US-ASCII
Content-transfer-encoding: 7BIT
Hi Layne,
You can estimate a sampling interval that meets a desired accuracy
specification based on linear interpolation.
Essentially you select a sampling interval (D) that is less that what you
expect the desired interval to be and observe a cross section through your
study area. Then using every second point (calculation interval is 2D)
estimate the height for each missing point. A height difference can then be
calculated between the estimated level and its known height. Complete the
estimation process for the length of the cross section and then calculate a
RMSE. If the RMSE is less than the accuracy required estimate the elevations
using a linear interpolation interval of 3D. Continue increasing the
interpolation interval until the RMSE is larger than the desired accuracy.
At this point you can calculate the desired sampling accuracy that meets
your height accuracy specification using linear interpolation.
If you have flat areas and steep areas that are clearly separate you can
repeat the process for each different terrain roughness area.
A more detailed description of the technique, including the math, can be
found in Balce, A. E., (1987), Determination of Optimum Sampling Interval in
Grid Digital Elevation Models (DEM) Data Acquisition, Photogrammetric
Engineering and Remote Sensing, Vol. 53(3), pp. 323 - 330
Cheers
Andrew H.
~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~
Andrew Hunter
PhD Candidate
Mobile Multi-Sensor Research Group
Department of Geomatics Engineering, The University of Calgary
2500 University Dr. N.W. Calgary, Alberta, Canada T2N 1N4
Tel: (403) 220 8785, Fax: (403) 284 1980
E-mail: ahunter@ucalgary.ca
-----Original Message-----
From: gislist-bounces@lists.geocomm.com
[mailto:gislist-bounces@lists.geocomm.com] On Behalf Of Layne Seely
Sent: Monday, January 26, 2004 7:29 AM
To: ARCVIEW-L@ESRI.COM: esri-l@ESRI.COM: gislist@lists.geocomm.com
Subject: [gislist] GIS Survey Question
hey Group:
I have been tasked with planning and performing a land survey to generate
contours for a project. We will be using the Leica SR530 to collect point
data to support the creation of 6" contours. The site may have as much as
10' total elevation above sea level (it's near the Yucatan peninsula :))
What I need to know is how closely I need to plan my points to warrant 6"
contours. From what I know of Lidar, you plan 2.5m postings to generate 2'
contours. If my math is correct, I will need to collect a posting every 2'.
Is this basically correct?
Mr. Layne Seely
GIS Analyst
CHIANG, PATEL & YERBY, INC.
1820 Regal Row, Suite 200
Dallas, Texas 75235
214.640.1736 (Direct)
214.638.3723 (Fax)
LSeely@cpyi.com
--Boundary_(ID_11nAFM2frLtiuFOo3Q+dBQ)
Content-Type: text/plain: charset="us-ascii"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
_______________________________________________
gislist mailing list
gislist@lists.geocomm.com
http://lists.geocomm.com/mailman/listinfo/gislist
_________________________________
This list is brought to you by
The GeoCommunity
http://www.geocomm.com/
Get Access to the latest GIS & Geospatial Industry RFPs and bids
http://www.geobids.com
--Boundary_(ID_11nAFM2frLtiuFOo3Q+dBQ)--
|
|
Sponsored by:
For information
regarding
advertising rates
Click Here!
|
