atul_salunke Posted April 26, 2011 Report Share Posted April 26, 2011 Hi all, I am trying to create bldging foot print using google images,but the images do not have top view,so some blding apperes tilted,this can be solved using ortho rectification(Not by georeferencing). does any know the process? Quote Link to comment Share on other sites More sharing options...
3dbu Posted May 10, 2011 Report Share Posted May 10, 2011 do you mean try to make a orthofoto take libe base the title or image took of Google earth...explain bether? Quote Link to comment Share on other sites More sharing options...
atul_salunke Posted May 13, 2011 Author Report Share Posted May 13, 2011 I have image taken from google earth..I need to do orthorectification on these images. Quote Link to comment Share on other sites More sharing options...
3dbu Posted May 13, 2011 Report Share Posted May 13, 2011 but if do you need orthorectification its should have overlay amount the imagery ...and then will need control ground point for make the orthorectifiction process....need more elements like focal distance, and other ...if you speak of orthorectification ...but is georeferencing there change the process....pleas be clear what really want for help in this direction. Quote Link to comment Share on other sites More sharing options...
pasfans01 Posted May 13, 2011 Report Share Posted May 13, 2011 orthorectificiation needs few expensive auxiliary data, like accurate 3D GCP,high quality DEM, RPC coefficient or orientation information, do you have it? Quote Link to comment Share on other sites More sharing options...
3dbu Posted May 13, 2011 Report Share Posted May 13, 2011 he had only title of google earth ....just that. Quote Link to comment Share on other sites More sharing options...
cseu Posted June 19, 2011 Report Share Posted June 19, 2011 Google images are already rectified, but only from a terrain point of view... of course this is not true orthophoto (the one you mean by viewing the buildings from the top)... you won't be able to do what you're looking for, you would need at least a pair of stereo images in order to extract a DEM that would allow you to produce a true ortho, lidar data would be better. My tip : considering that the ground surface is ± rectified, draw your footprint from the base of the buildings and guess the 4th point (hidden by the tilted building) according to the apparent building geometry and 90° angles in most of the cases. Of course this is real approximate job, considering the georeferencing of google images which is sometimes strange... then again it depends on the imagery quality in the area you're working on. Quote Link to comment Share on other sites More sharing options...
bpetkovic Posted May 21, 2012 Report Share Posted May 21, 2012 global mapper can help but you must learn how to ortorectify first Quote Link to comment Share on other sites More sharing options...
murex Posted June 20, 2012 Report Share Posted June 20, 2012 It is not impossible but very hard. You need many control point and it depends of the terrain too. :cool: Quote Link to comment Share on other sites More sharing options...
hadiwibowo Posted July 13, 2012 Report Share Posted July 13, 2012 u can try stitchmap .... Quote Link to comment Share on other sites More sharing options...
arcsump Posted July 13, 2012 Report Share Posted July 13, 2012 i guess you have to mosaic the image, georeference them then check with ground data from GPS. that is the standard way to do it. Quote Link to comment Share on other sites More sharing options...
Capricorn Posted July 16, 2012 Report Share Posted July 16, 2012 @atul_salunke Ortho rectification is a proces in photogrammetry that converts 3D image to ortho projection, no 2D image to 2D image. To get 3D image from a stereo pair, you should have as many GCPs as possible to drape this image precisely to the terrain. Once I did a job of stiching simple aerophotos (not stereo pairs, but images of 10% overlap) by rectifying them, but that was long lasting job in urban areas with high buildings. I used polinomal rectification in Raster Design. Always save points and keep original image files. After rectification you may see some mistakes in final image. Then you should add even more control points in the areas with mistakes and process agein. And all the way until you are sattisfied with the result. Quote Link to comment Share on other sites More sharing options...
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