Merging Corona Images in ArcMap

This is specifically for Corona Images, but will work for any image. You just have to be careful on point 20. This information is specific for Corona – if you have another image you will have to change the information accordingly.

1. Open ArcMap 2. Open New Empty Map 3. Click File/Save as and save your project under a suitable name 4. Click File/Add data 5. Browse to the folder where you saved your image files and open them (Ex. A+B). 6. Arcmap will ask you if you want to make pyramids. This is not necessary. 7. Arcmap will inform you that the images have no georeference. They can therefore be drawn in ArcMap, but not projected. We will get to that later. 8. Open View/Toolbars/Georeferencing and View/Toolbars/Effects 9. Open the Rotate icon (circle) on the Georeferencing toolbar – change that to shift (arrow and square). You can now move the image that shows in the scroll-window separately (default file A). Arrange them side by side the way they should be merged. Zoom in to the top of that area. 10. Find a static point in both images. Ideally a cross-hair, but if there are none, chose an intersection, airfield, large building etc, that you can assume have not changed its position. Change brightness (sun) and/or contrast (black-white circle) on the effects toolbar if necessary to get a clearer image. 11. Click on the add control points icon (a dash with a red and green cross at the ends).Click once on your point on file A. 12. Click on the pan (hand) and pan over to the same point on the other image, file B. Zoom in if necessary. 13. Click on the add control points icon again. Click once on your point on the other image, file B. The image will now align. 14. Pan to the lower part of the image, repeat 10-13. 15. With the Effects Toolbar you can scrutinize your results by either clicking on the Transparency icon (water jug) and change the transparency of the topmost layer and/or clicking on the Swipe Layer icon (line with arrow underneath) which will enable you to “roll” the layers back and forth. 16. Right-Click on the files in the layers window. Choose properties. A new window will open showing (among other things) the cellsize. Copy the cellsize. Click OK. Make sure the cellsize is the same for the two images. 17. Open Georeferencing/Rectify. A new window will open. Paste the cellsize from point 15 into the cellsize window. Use default resampling. Choose a new name for your file, ex. Rectify_AB. 18. Click red toolbox icon or Window/ArcToolbox 19. Open Data Management Tools/Raster/MosaictonewRaster. A new window will open. 20. Enter as the following: Input rasters – File AB and file B Output location with extension - Example H:/Your Folder/Mosaic_AB.tif Coordinate system – skip (unless the images are projected of course) Pixel type - 8_bit_unsigned (=default) Cellsize – Paste the cellsize from point 15 Number of bands – 1 (if it’s not corona, there might be more layers) Mosaic Method – BLEND (= will make the transition smoother, not ) Mosaic Colormap Mode – FIRST (=default) 21. Click OK 22. After about 15 minutes your merged file will be ready. Serve with ketchup and fries.