Following on from the GEMS Tips post on how to generate a surface and contour areas without data, we would now like to share how to drape an image over a surface.
Steps to drape an image over a surface
1. Open the surface that you wish to drape the image onto and center the surface in the display window and be sure that the area you want to drape with the image is visible. It is recommended that to have the surface displayed in 2D mode, especially when creating ties manually by clicking.
A spilt screen will appear with the image displayed on the left and the surface on the right.
4. Create tiepoints (registration points): Click first on the image then the corresponding point on the surface. Try to pick points that represent features easily on both image and DTM. Repeat for at least 3 points or as needed. If using World X,Y, and Z coordinates for the point on the image, thay can be manually entered in the table below the image.
Tip: Do not click on the edge of the image, as it will not register properly. Try to be as precise as possible to avoid skewing the registration of the image.
5. If all registration points have been defined, go to File > Save As. The file should be saved in the same host folder as the original image. The new file will be saved as a .rimg file.
Tip: Save host image and .rimg file within the GEMS project folder to follow best practice and ensure the link remains established between host image and .rimg file (as the host image could be moved unintentionally)
6. Exit the split screen by going to File > Close Editor.
7. To link the image to the surface, right-click on the surface, and choose properties. On the right-hand side of the dialog box, you will see the display options. Check on ‘Drape a registered image on the surface’. Using the ellipse navigate to the .rimg file that was just created. Press ‘Open’. Then press ‘OK’. The draped image will appear on your graphical work-space area.
Tip: If you image draped on the surface appears white- try resizing or compressing the file. It is likely the image is too big. Some definition maybe lost but this method allows the function to process the image.