[GRASS-user] rectifying digital images

[Vincent BAIN]

Hello Maning,
Yes the actually important data concerns the camera properties. I fear
your images won't be easy to handle : I guess your camera is not
properly an aerial survey camera system, is it ? each image should show
fiducial marks on its edges, and you should have a calibration
certificate providing data such as focal length, fiducial marks position
and so on.
Let us know a bit more about the camera.


Le samedi 05 janvier 2008 à 15:24 +0800, maning sambale a écrit :
> Hi,
> 
> I have a lot of aerial photos I need rectify.  The data came from an
> incomplete project intending to acquire geospatial data for landslide
> risk assessment.
> The project ended prematurely.
> 
> Here are the details:
> Images were acquired using this method.
> 
> Two GPS receivers were used, one attached to the laptop to facilitate
> the navigation of the
> airplane and the other to the camera to determine the geographic location of the
> center of the photographs. The plane flew along the flight lines
> indicated in the plan.
> The photographs were taken along the flight line using a professional
> Kodak N14 digital
> SLR camera, which has a resolution of 14 megapixels. The camera was
> fastened to a
> mount, made from plywood and customized to accommodate the camera and the laptop
> computer. The seat next to the pilot was detached to make room for the mount. A
> camera door, designed specially for this purpose, replaced the normal Cessna 172
> passenger door.
> 
> What do I have now:
> over 800 photos
> GPS point location for each photo
> Quickbird image of the whole study area
> 
> According to their report:
> There is difficulty in mosaicking the photographs. The
> original plan was to stitch the photographs together to create a
> composite image.
> But the tilt in the photographs due to the movement of the aircraft
> requires that
> certain adjustments be made.
> 
> Any ideas on how to resolve this.  As far as I know, you need certain
> camera parameters to orthorectify aerial photos
> CAMERA NAME:               camera name______
> 	CAMERA IDENTIFICATION:     identification___
> 	CALIBRATED FOCAL LENGTH mm.:_________________
> 	POINT OF SYMMETRY (X)   mm.:_________________
> 	POINT OF SYMMETRY (Y)   mm.:_________________
> 	MAXIMUM NUMBER OF FIDUCIALS:_________________
> 
> 
> How do I get this?  Is it OK to rectify the imges from the quickbird
> satellite data?
> 
> cheers,
> 
> maning
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