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| GeoCommunity Mailing List |
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| Subject: | RE: [gislist] Viewshed mapping |
| Date: |
11/05/2003 11:20:01 AM |
| From: |
Richard Nicoll |
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Hi Erika,
I would suggest using ERDAS, ER Mapper, or 3D Analyst for ESRI. These '3D'=
packages will allow you to build a 3d model of the area. You would need e=
levation data, building outlines (MasterMap) and building heights (GeoInfor=
mation Group). If you used LiDAR or NEXTMap you could get all 3 from one s=
ource, as a DSM. You can then combine all these and generate a viewshed fr=
om the camera x,y,z position. This will then identify areas which are not =
visible ('shadows' where an object blocks the view), and produce a sphere a=
round the camera position in the centre.
Then you can calculate the degree of movement of the camera (panning up/dow=
n, left/right, and zoom) to crop the sphere into a 'wedge' which basically =
removes anywhere beyond the camera movement angles. For improved accuracy =
you could even model the lens!
To piece it all together most GIS packages allow you put a URL (if the came=
ra image is online) or a file pathname (if you have a static image) as an a=
ttribute to the polygon. Then configure the query tool to use this attribu=
te, and when you click on the shape you will get the image to open up.
Hope this is of use,
Rich
-----Original Message-----
From: epoulsen@eden.rutgers.edu [ mailto:epoulsen@eden.rutgers.edu]
Sent: 05 November 2003 16:46
To: gislist@lists.geocomm.com
Subject: [gislist] Viewshed mapping
Hello all!
I have a research problem that I am wondering if you could give me some
advice or point me to the information that would help.
There are a few shopping centers with security cameras that look out on
to the parking lots, as well as other parts of the property.
I am interested in using a GPS to locate the XYZ coordinates for the
cameras, and then create digital polygons for the extent of views that
the camera provides on the ground. I know that I am going to have to
take into consideration the zooming and panning of the camera. The
goal is to be able to click on a polygon view and obtain a view from
the sensor.
Thank you!!
Erika
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