Quick Georeference is a fast method to georeference an image. This method requires two conditions:
- The image is not rotated (image aligned to True North)
- Only two points are needed to georeference, however these points must not contain the same coordinate in either the X or Y pixel or world unit (i.e. two points cannot be aligned on the same X or Y axis on either the image or world system)
In this tutorial, you're going to Quick Reference an image to the WGS 84 coordinate system.
1.In Adobe Photoshop, open Americas_4.tif from the Tutorial Data folder.
The image is unreferenced. It also meets the two conditions noted above: 1) it isn't rotated and 2) it is aligned to True North.
2.In the Geographic Imager panel, click the Georeference button.
3.On the Georeferencing dialog box, to the left of the image view, click the Add Control Point button. Click anywhere on the image view to add a point.
Point 1 is added to the control point list. You'll adjust the pixel coordinates (PX and PY) and add world coordinates (WX and WY).
4.Double-click the PX cell and enter 599. Double-click the PY cell and enter 0.
5.Double-click the Coordinate System, WX, or WY cell.
6.Choose the WGS 84 coordinate system. Enter 35.917 into the Lat box and enter -50.064 into the Long box, then click OK.
The world coordinates are updated in the control point list
7.Add a second point to the image view. This time, use the pixel coordinates: PX = 0, PY = 456; and use the world coordinates: Lat = 6.731, Long = -88.417.
Now that two control point pairs are ready, you'll next use the Quick Georeference feature.
8.Click the Image Coordinate System Specify link.
9.On the Choose Coordinate System dialog box, click the [No Coordinate System Specified] link.
10. In the Specify Source Coordinate System dialog box, expand the Coordinate Systems > Geodetic > World category, select the WGS 84 coordinate system and click OK.
11. Click OK to close the Choose Coordinate System dialog box.
12. Click the Quick Georeference button and select the option By Two Reference Points (North/South aligned).
An additional control point is added to the control point list and image view. Its world coordinates were calculated based on the existing two control point pairs. A minimum of three control points are required to reference the image.
13. Click OK to complete the georeference.
The document has been successfully georeferenced.
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