SMS:Electronic Charts

Since surveys can be expensive to obtain, and DEMs may not be applicable, another option available for the hydraulic modeler is the use of topographic/bathymetric charts or historic nautical charts. If these types of maps can be digitized into an electronic format, they can be read into SMS and displayed on the screen. The goal is to create a scattered dataset from this electronic chart. The steps to do this include:

1. Scan the paper map and save it as an image (*.tif, *.jpg, ...).
2. Register the image (you may want to mark the map with your register points prior to scanning it).
3. Select the Create Vertex tool in the Data Module.
4. Digitize (click on the image on the screen) to create a vertex on a contour line in the image.
5. In the z edit box of the edit window set the z value to the contour value of the line.
6. Digitize along the specified contour value (the spacing of points along the contour lines should be approximately the same distance as the spacing between adjacent contours).
7. Repeat steps 4–6 for each contour line. Spot elevations can be entered by setting the z value to the value of the spot elevation and then creating a vertex at that location.
8. Triangulate the vertices once you are done.

This method becomes tedious for larger areas, but is ideally suited for smaller areas where there are not too many contours to be digitized.

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