1
General / View-dependent texture project and the Camera extrinsic/intrinsic properties
« on: September 25, 2015, 07:28:20 PM »
Greetings!
We have been trying to work with the data stored in the standard XML file of camera positions along with the 'undistorted photos' that can be produced from the export menu to do some view-dependent texture mapping. The idea is, the individual views can be precisely projected back onto the geometry and cleverly blended to produce very realistic material appearances (see Buehler et al.'s Unstructured Lumigraph and derivative works).
So far we've had a lot of success doing this. PhotoScan calibrates all the views and computes the appropriate extrinsic camera properties that we can extract from the XML camera data. Additionally, we can take care of any intrinsic camera properties essentially with the 'undistorted photos' option that removes all camera distortion. We are also able to get the model and these views in alignment using the global rotation, translation and scale values in the XML file if any are included.
However, we have found one combination of transformations that we cannot seem to handle consistently. If the object includes both a global rotation AND a global scale (caused by rotating the object to align it with the axis and then scaling with scale bars) we cannot get the proper projection for the individual views no mater how we treat the matrices and combine them.
My current suspicion is that there is something happening with the 'undistorted views' that we are not fully accounting for. Can anyone provide any insight into the FULL model that is being applied when you do 'undistorted views' from the export menu? I can find bits and pieces of it around in libraries like OpenCV but none of them account for all of the parameters that are listed for camera intrinsic properties in the XML file. Also, some more technical explanation of the options in this 'undistorted views' export dialog (like the 'square pixels' checkbox) and how they might be relevant to our target application, VDTM, would be very useful.
And of course, this might have nothing to do with the undistortion process so if there any other ideas anyone has I'm all ears!
Any thoughts or assistance would be very much appreciated!
Seth Berrier
We have been trying to work with the data stored in the standard XML file of camera positions along with the 'undistorted photos' that can be produced from the export menu to do some view-dependent texture mapping. The idea is, the individual views can be precisely projected back onto the geometry and cleverly blended to produce very realistic material appearances (see Buehler et al.'s Unstructured Lumigraph and derivative works).
So far we've had a lot of success doing this. PhotoScan calibrates all the views and computes the appropriate extrinsic camera properties that we can extract from the XML camera data. Additionally, we can take care of any intrinsic camera properties essentially with the 'undistorted photos' option that removes all camera distortion. We are also able to get the model and these views in alignment using the global rotation, translation and scale values in the XML file if any are included.
However, we have found one combination of transformations that we cannot seem to handle consistently. If the object includes both a global rotation AND a global scale (caused by rotating the object to align it with the axis and then scaling with scale bars) we cannot get the proper projection for the individual views no mater how we treat the matrices and combine them.
My current suspicion is that there is something happening with the 'undistorted views' that we are not fully accounting for. Can anyone provide any insight into the FULL model that is being applied when you do 'undistorted views' from the export menu? I can find bits and pieces of it around in libraries like OpenCV but none of them account for all of the parameters that are listed for camera intrinsic properties in the XML file. Also, some more technical explanation of the options in this 'undistorted views' export dialog (like the 'square pixels' checkbox) and how they might be relevant to our target application, VDTM, would be very useful.
And of course, this might have nothing to do with the undistortion process so if there any other ideas anyone has I'm all ears!
Any thoughts or assistance would be very much appreciated!
Seth Berrier