Map images as source of digital maps

Q. Can WAsP or the WAsP tools handle paper maps or digital map images so as to convert them into digital vector maps (digital terrain models) required for wind resource estimation with WAsP. If yes, how does the procedure work?

A. Yes, the WAsP Map Editor can be used to perform this job. In case of paper maps we recommend to use paper maps at a scale of 1:25,000 or 1:50,000. Of course, larger scales are also possible, but the work will be very tedious. If the digital map is acquired in another way, please get it in *.jpg or *.bmp-format.

In short the procedure is as follows:

• If the source is a paper map, the paper map is scanned to a digital image in *.bmp or *.jpg format, using a normal office scanner (20 by 30 cm scanning area or larger). A resolution of 300 dpi (1:25,000) or 600 dpi (1:50,000) is fine. A colour resolution of 256 colours (using a colour palette) is sufficient – but a full 24-bit color resolution ("Millions of colors", "Sharp color photos" or the like) will also work fine, but will take up more file space.
• No matter how the digital map image was acquired, in the Map Editor the digital map image is opened as a "background map", and through a calibration procedure the true map coordinates of the background map are defined.
• Digital representation of height contours and boundaries between different roughness areas are produced by an on-screen digitization procedure, where one clicks on the screen image of these terrain features.
• When finished, the digitized terrain information is saved as a WAsP vector map (*.map).

Q. How large a background map can be handled by the WAsP Map Editor?

A. The maximum size depends on the RAM memory available in the computer when loading the background image. The limit is  approximately:  (Number of pixels) * 4  <  ½ * (Available RAM memory in bytes). 

Back to Frequently Asked Questions page