Chris Proba - orthorectification VIRGINIA ELENA GARCIA MILLAN http://www.brockmann-consult.de/cms/cms/c/message_boards/find_message?p_l_id=10944&messageId=59628 2011-11-14T12:47:30Z 2011-11-14T12:47:30Z

Hi Ralf!<br /><br />I found in the BEAM Help that the data format for the GETASSE30 DEM is <div class='quote'><div class='quote-content'>binary, 1800*1800 signed 16-bit integer values, big endian order</div></div>. If I want to use the ASTER DEM, I have to be sure that the format is the same, right?<br /><br />Concerning that the resolution of the GETASSE30 DEM is 30 arcsec, if I define the Target altitude in the GPC points manager with a better resolution DEM, as ASTER&#039;s, activating &#034;use target altitude&#034; should provide better accuracy than the GETASSE30 DEM in the orthorectification tool, right?<br /><br />What is your opinion?<br /><br />Thank you for your previous answers!<br /><br />vir

VIRGINIA ELENA GARCIA MILLAN 2011-11-14T12:47:30Z Ralf Quast http://www.brockmann-consult.de/cms/cms/c/message_boards/find_message?p_l_id=10944&messageId=59566 2011-11-14T08:48:50Z 2011-11-14T08:48:50Z

Hi Virginia, the correct sequence for doing the orthorectification of CHRIS/Proba images is:<br /><br /><ol style='list-style-type: decimal';><li>Define ground control points for your scene</li><li>Do the CHRIS/Proba geo-correction</li><li>Do the orthorectification by means of the BEAM reprojection tool</li></ol><br /><br />The ground control point have to use WGS 84 coordinates, and be sure that you do not use the target altitude when doing the geo-correction. Unfortunately you cannot use the ASTER DEM instead of the GETASSE30 DEM, unless the file formats are the same.<br /><br />The tie point grids resulting from the CHRIS/Proba geo-correction tool provide viewing angles and latitude &amp; longitude per pixel (each pixel is a tie-point). When they are reprojected, they become usual band, but you do not need to reproject the tie points anyway.

Ralf Quast 2011-11-14T08:48:50Z VIRGINIA ELENA GARCIA MILLAN http://www.brockmann-consult.de/cms/cms/c/message_boards/find_message?p_l_id=10944&messageId=59487 2011-11-11T20:16:50Z 2011-11-11T20:16:50Z

Hi again!<br /><br />in the line of my previous post (geometric correction / telemetry file), what I really want to do is to orthorectify a Chris Proba image. As I undertood by the BEAM Help, the sequence is:<br /><br />1) First, use the Chris Proba geometric correction tool using a telemetry file<br />2) GPC points have to be defined on the image (the resulting image of the geometric correction tool)<br />3) Use the orthorectification tool<br /><br />Is this procedure correct? Once you put GPC points on the displayed image, the orthorectification tool recognize them?<br /><br />About the orthorectification tool I have some extra questions: <br /><br />a) can I use another DEM different to GETASSE30 Elevation Model? I would like to use an ASTER DEM<br /><br />b) what are the tie-points grid? what are the implications of reprojecting them? <br /><br />Thank you very much and sorry for the avalanche of questions!<br /><br />virginia

VIRGINIA ELENA GARCIA MILLAN 2011-11-11T20:16:50Z