shrug-l: Spatial Extent problem using the cost distance function with point and raster datasets.

Yurong Tan tany at gisgo.com
Fri Jun 8 16:20:28 EDT 2007


You can create a feature class in a PGDB with the same type of features and
projection as the shapefile, but using a new extent (Xmin, Ymin, Xmax,
Ymax).  You need to select the new extent in a way that will ensure the
existing shapefile will fit into the center area of the new extent while
leaving enough space (spatial extents) for new features to expand in all
four directions.  Then you can import the features in the existing shapefile
to the new feature class or copy the features and paste them to the new
feature class.  This is probably the simplest, yet sure way to solve the
problem.  Copying projection file around may or may not work depending on
the relative extents of the shapefile to be copied.   

 

Also keep in mind that extending/expanding feature layer extent is normally
done at the expense of loss positional accuracy because there is a limit on
the number of coordinate units in PGDB/SDE.  Normally, this limit is not a
concern as long as you are not dealing with nation-wide data layers.

 

Hope this helps.

 

 

-----Original Message-----
From: shrug-l-bounces at lists.dep.state.fl.us
[mailto:shrug-l-bounces at lists.dep.state.fl.us] On Behalf Of Wolfe, Heather
Sent: Friday, June 08, 2007 1:46 PM
To: Swett, Bob; shrug-l at lists.dep.state.fl.us
Cc: gunnsys
Subject: RE: shrug-l: Spatial Extent problem using the cost
distancefunctionwith point and raster datasets. 

 

There is a really easy way to do it. 

 

-make a copy of the shapefile (needs to be a shapefile- it it's a feature
class export to a shapefile)

-delete the  .prj file

-find or make another shapefile that is the same projection but larger
extent. for instance, if I wanted one that was a little larger than seminole
county, I would get a SPFLE county file of all the florida counties, select
seminole and all the counties around seminole, and export them to a new
shapefile . 

-Import the projection from the larger shapefile (the extent will come also)

 

you can also play around with the extent settings,  but that can be a little
messy. I advise doing it the easy way. 

 

Heather Wolfe
Sr. GIS Analyst, Planning & Development
Seminole County Government
1101 E. First St.
Sanford, FL 32771

Office 407-665-7378
Fax 407-665-7412
HWolfe at seminolecountyfl.gov
www.seminolecountyfl.gov

 

 

  _____  

From: Swett, Bob [mailto:rswett at ufl.edu] 
Sent: Thursday, June 07, 2007 3:19 PM
To: shrug-l at lists.dep.state.fl.us
Cc: gunnsys
Subject: shrug-l: Spatial Extent problem using the cost distance
functionwith point and raster datasets. 

A colleague is using the cost distance function with a raster and a point
dataset as inputs. The extent of the point dataset seems to be controlling
the output. How can he change the extent (i.e., we want to extend some
distance beyond the point dataset extent). 

 

Any help is greatly appreciated (he wants to embed this within a DLL).

 

Thanks

Bob Swett

____________________________________________________________________________
_________________________
Bob Swett  |  Coordinator  |  Florida Sea Grant Boating and Waterway
Management Program  |  www.flseagrant.org <http://www.flseagrant.org/> 

Assistant Professor | Department of Fisheries and Aquatic Sciences |
Institute of Food and Agricultural Sciences-UF 

PO Box 110405     |    Gainesville, FL 32653    |     *:352-392-6233    |
Fax: 352-392-5113    |    * rswett at ufl.edu 

 

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-****Florida has a very broad Public Records Law. Virtually all written
communications to or from State and Local Officials and employees are public
records available to the public and media upon request. Seminole County
policy does not differentiate between personal and business emails. E-mail
sent on the County system will be considered public and will only be
withheld from disclosure if deemed confidential pursuant to State Law.****-

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