|
|
| GeoCommunity Mailing List |
| |
| Mailing List Archives |
| Subject: | Re: [gislist] Orthoimagery |
| Date: |
05/10/2004 08:05:01 AM |
| From: |
Jayachandran Mani |
|
|
hi
aerial photography @ 1 : 400 scale is quite a good
resolution. It is amazing to have the photography done
at this scale.
Colour balancing between two different flightlines is
a major task in photogrammetry.
The fuzzy appearance may be due to the dodging
parameters used during the mosaicing process or it may
be due to the improper positional accuracy of the
features between the orthos from different flightlines
/ models in the same flight line.
It is always suggested to have the ortho created for
the center of the photograph to avoid the relief
errors (as the scale of photography is large) and to
avoid the distortion errors at the peripherals. i.e
instead of creating ortho photos for one model
completely (with one/two underlying images of the
model), the ortho should be created for the central of
the photograph. For this DEM may have to merged for
the adjacent models. Initial planning of this may sort
this issue. This way may solve the positional
inaccuracies.
For colour balancing, orthovista will be good.
Recently we had an experience of creating a seamless
ortho mosaic in LPS (leica photogrammetry suite),
which was excellent. but it was a b&W imagery. For
colour, atleast within the mosaic, we can be able to
get a seamless mosaic, with more extra care
(considerable time). Photoshop may also have to be
used extensively sometimes.
regards
Jay
--- Ron Lake <rlake@galdosinc.com> wrote:
> Eric Sandoval wrote:
>
> >Hello Listers:
> >
> >I have a question for the orthoimagery experts out
> there. We have imagery that exhibits substantial
> radiometric inconsistencies. Our imagery was flown
> at 1:400 scale or 6 inch resolution. The various
> flight lines were merged and then were processed to
> choose the best image based on sun angle,
> clarity,etc. The images were then color balanced.
> >
> >Our problem: Along the seems of our imagery a
> distinct difference can be seen. On one side of the
> seem the ground features will appear clear and on
> the other side they appear fuzzy. We were told by
> the survey company that these differences were the
> result of different flight lines. The difference in
> contrast, clarity and sharpness are a function of
> flight lines were taken at different times of the
> day and the position of the features. Some features
> are on the outer portion of the flight line and
> therefore exhibit lean due to camera angle. Flight
> lines were planned with a standard 60/30 overlap.
> >
> >My question: Can't these problems be resolved
> through processing or surveying additional flight
> lines? I understand it's unreasonable to acquire
> additional flight lines after the initial survey
> (cost prohibitive), but couldn't additional flight
> lines been planned if these problems were known in
> advance (which they were)? Does this type of
> problem occur in all orthoimagery?
> >
> >Any insight or comments that you can provide would
> be most appreciated.
> >
> >Thank you,
> >
> >-Eric Sandoval
> >
> >
> >
> >---------------------------------
> >Do you Yahoo!?
> >Win a $20,000 Career Makeover at Yahoo! HotJobs
> >_______________________________________________
> >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
> >
> >
> >
> >
> Hi,
>
> You might start by a simple histogram equalization
> applied to the area
> across the image boundary.
>
> Cheers
>
> Ron
> _______________________________________________
> 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
__________________________________
Do you Yahoo!?
Win a $20,000 Career Makeover at Yahoo! HotJobs
http://hotjobs.sweepstakes.yahoo.com/careermakeover
_______________________________________________
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
|
|
Sponsored by:
For information
regarding
advertising rates
Click Here!
|
