Step 1. Load and Georeference the Image
Click Home | New Map | Base, select your image file and click Open. This will load the scanned image map into Surfer as a base map. If the image was already georeferenced, you can skip to Step 2. If the image is not already georeferenced, you can georeference the image base map, by using one of these methods:
- If you know the real world coordinates of the image corners, follow the steps in this article: How Can I Georeference (Assign Coordinates To) An Image Base Map In Surfer?
- If you don’t know the corner coordinates, but know 3 points interior to the image, you can use the instructions in this article: How can I create a georeferenced base map from an unreferenced image file in Surfer?
- If you don’t care what your X and Y coordinates are, you can simply leave the coordinates as they are in pixel units (0,0 in the lower left corner).
Step 2. Digitize the Image and Create the XYZ Data File
- Select the map and click Home | Add to Map | Layer | Empty Base. This adds a new base layer to the map.
- Right-click the new empty Base layer in the Contents window and click Edit Group.
- Digitize the first object. If you are digitizing point locations, click Features | Insert | Point and click on the map on the first point location. If you are digitizing contour lines or other lines, click Features | Insert | Polyline and trace the line on the image.
- After the first object is created, expand the Base layer in the Contents window, right-click it and click Open Attribute Table.
- In the Attribute Table window, click the green + button to add a new attribute field.
- For the Attribute name, enter ZLEVEL to assign the Z value for the object and click OK.
- For the object you drew, enter the Z value for that object in the Attribute Table under the ZLEVEL field.
- In the plot window, draw the rest of the objects. For each object you draw, enter the Z value for that object in the Attribute Table under the ZLEVEL field.
- Once all the points or polylines have been digitized, right-click the Base layer in the Contents window and click Stop Editing Group.
- Turn off the axes and all the other map layers (so you just see the digitized data on the screen) by unchecking them in the Contents window.
- Click File | Export, give the file a name, choose to save the data as DAT XYZ points (*.dat, *txt, *xyz) file, and click Save.
Step 3. Grid the XYZ Data
- Click Home | Grid Data , select the DAT file you just created and click Open.
- Specify any gridding options you want and click OK. This will create the grid file.
Step 4. Create the Contour Map
- Click Home | New Map | Contour, select the grid file you just created and click Open. This will create the contour map.
- Select the Contours layer in the Contents window, and change any of its properties in the Properties window.
Updated January 31, 2017