Selecting a Geographic Coordinate System from a file in raster manager

Question

How to select a coordinate system from a DGN file in raster manager for .ecw image. The option available is to select it from library but the coordinate system is not on the library list and I can not edit the library list without Bentley Maps. Please assist.

Jon AR · Answer

Hi Ncedom, 
 
With no Bentley Map as you said you cannot edit the library list but you could try to find the most similar coordinate system in the list and compare how much the differences in the meassures are between them, the difference must be suitable depending on the accuracy needed in the Project. 
 
Hope this helps.

Lorys · Answer

If you have accurate survey in a datum you can use then you can ref attach that to a dgn with same datum set then raster manager attach the ecw just by interactive, 2 diagonal points then warp the raster in raster manager by points the more points you can find around the outer edges to match the cadaster or survey the better accuracy the warping will become once you have enough points detach the cadastre or survey and rename your dgn as XYZ Datum Photography Area name.dgn 
 This depends on scaling as how accurate you can get this as you have to eyeball manual snapping to a pixel in the ecw to get the warping to align with cad real snaps... 
 You can now use this Dgn as your airphoto file and it will geo ref to any known listed datum...and use the ref manager to attach it reprojected, or world coincedent if same datum... 
 I dont know if you can export the warped ecw to say Jpeg with a sister file but worth a shot.. 
 there is another method which you creates monument points against known coordinate points ie you know the coordiantes of a round about or a series of pits and these are visible in the raster and you know where they are in the coordinate world and cad file and also in the photo by eye... this is much more complicated method but yeilds better results for accuracy...and I think it remembers the datum you set it too and can be set to the ecw... ( not sure about that, its more for making new un registered datum equivalents).. but I know the first method works very well for areas that are not too big, lots of points and good easy to locate cadastre or survey...