|
|
| GeoCommunity Mailing List |
| |
| Mailing List Archives |
| Subject: | GISList: Image Rotation Problem |
| Date: |
02/13/2002 10:00:17 AM |
| From: |
Anthony Herman |
|
|
Hello List. I have an interesting problem that does not seem to have an
easy solution. We maintain hundreds of orthophotos in our GIS system. We
are now going to mobile (labtop) gis solutions, but in order to save disk
space we need to shrink the orthos down to a manageable level.
The obvious solution is to use MrSid or ERMapper to compress the TIF images
and simply reinsert them into our GIS system. The problem is that our
orthos have a rotation value in the associated TFW or world file. This
world file is not correctly interpreted by MrSid or ERMapper - from what
tech support has told me they do not support rotation - @ least reading it
from the world file like a GIS system would. In addition, the rotation value
is lost in the new world files associated with Sid or ER output formats.
Thus rotating after the fact is not possible.
What to do? Here is some additional info:
Photos have varying rotation values... from say 10degrees to 90 - to
facilitate the way they were flown - along a 2km corridor that varied in
direction.
Photos are TIF file format with world files - TWF's - not geotiffs.
One solution that worked, but resulted in lost resolution was using
ArcView's Image Analyst and mosaicing the photos and then converting the
mosaiced IMG file with MrSid to a sid image - as ArcView will properly read
tif TWF's and align all the TIF's.
Thanks for any response.
Cheers,
Anthony Herman
Anthony Herman
Land Management Group
Pipeline, Field & Business Services Division
Westcoast Energy Inc.
604 691 5197
To unsubscribe, write to gislist-unsubscribe@geocomm.com
________________________________________________________________________
Setup a GeoCommunity Account and have access to FAST DataDownloads
and Premium Career Posting at a discounted rate!
https://www.geocomm.com/cgi-bin/accounts/login
On-line Archives available at
http://spatialnews.geocomm.com/community/lists/
|
|
Sponsored by:
For information
regarding
advertising rates
Click Here!
|
