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| GeoCommunity Mailing List |
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| Subject: | RE: [gislist] Imagery vs. GIS scale |
| Date: |
12/08/2004 04:25:01 PM |
| From: |
Karen Morley |
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Hi Anthony,
This is more than a function of the image resolution. It is also based =
on the accuracy of the rectified image. For a good guideline please see =
the National Map Accuracy Standards here:
http://rockyweb.cr.usgs.gov/nmpstds/nmas.html
-Karen
-----Original Message-----
From: gislist-bounces@lists.geocomm.com
[mailto:gislist-bounces@lists.geocomm.com]On Behalf Of Anthony
Quartararo
Sent: Wednesday, December 08, 2004 8:59 AM
To: gislist@lists.geocomm.com
Subject: [gislist] Imagery vs. GIS scale
I've probably asked this one before, I cannot remember whether I have =
or
not, so my apologies if this is redundant. What would be the maximum
least-common effective RF scale of a GIS dataset that was digitized from =
a
1m color orthorectified satellite image ? Put another way, if we use a =
1m
color ortho satellite image to extract features (ie. Roads or rivers) =
and
create layers in a GIS, what would be the largest scale that the =
resulting
GIS dataset would have with any degree of confidence ? For example, a 1m
image can be "zoomed" in when viewed in ArcInfo, to a "scale" of 1:2000 =
and
all the desirable features are clear and crisp, ready for "digitizing" =
and
extracting. If this scale of 1:2000 of the imagery is kept consistent
during the digitization, what would be the resulting RF scale of the GIS
data that was digitized ? Is there a formula to work this out for =
varying
scales of the image "zoom"? Thanks in advance.
Anthony
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