GeoCrop Tutorial – Avenza Systems

The GeoCrop function crops georeferenced images based on defined crop areas.

1.In Adobe Photoshop, open Americas_1.tif from the \Tutorial Data\Americas folder.

2.On the Geographic Imager panel, click the GeoCrop button.

3.Click the Crop by Extents button.

4.Choose Image Coordinate System from the Use drop-down list and choose Decimal degrees from the Format drop-down list.

5.As the Minimum, enter 39.50 in the Lat box and -122.50 in the Long box.

6.As the Maximum, enter 62.50 in the Lat box and -91.50 in the Long box.

geocrop_values

The maximum and minimum coordinates form a crop area designated by the red dashed marquee. This functions similarly to the Adobe Photoshop Crop Tool except it uses precise geographic coordinates to determine the crop extents.

7.Click OK.

The preview is immediately cropped based on the crop extents specified.

8.To manually resize crop area, click a corner or edge of the marquee and drag to resize it.

geocrop_marquee

The dimensions and corner coordinate values are updated. This can be used as a quick way to crop an image to an area of interest.

geocrop_valuesupdated

9.Right-click the preview image near the center and select Crop by Position.

geocrop_rightclick

10.Under Dimensions, enter 10 degrees as the Width and 12 degrees as the Height.

geocrop_byposition

The base point coordinates was determined by the right-click. The point is located in the Center and the dimensions create a proximity around that point. The base point can be changed to fine tune the GeoCrop. Similarly, a crop area is designated by the red dashed marquee in the preview.

11. Click OK.

The preview is immediately cropped based on the crop extents specified.

12. Click OK to complete the GeoCrop.

Screenshot 2024-09-18 160211.png

The image is cropped to the area specified in the GeoCrop dialog box. It's also possible to use the Adobe Photoshop Crop Tool to crop images. Geographic Imager will respect crops made by the Crop Tool and maintain proper spatial referencing. The Crop Tool is useful for situations where you prefer an spatial image to be a particular size because it has settings for dimension and resolution (W x H x Resolution).