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Measure Areas

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Revision as of 20:35, 10 June 2014 by Ferdi (Talk | contribs)

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How to measure areas in map

Image imported into Librecad

Given: map with scale, see example picture (source: Openstreetmap)

  • Create new layer
  • "Draw / insert image"
  • Measure scale: 500 m (scale) are 83.6 units in Librecad ("Dimension / horizontal")

Solution 1: Rescale your measurements

  • 1 unit (LC) == 5.98 m (500 / 83.6)
  • If you measure areas: 1 unit^2 == 5.98 * 5.98 m^2
  • After measuring convert "units" into meter.

Solution 2: Rescale your image

  • Select the layer where image was imported
  • 500 m are 83.6 units. If you prefer "500 m == 50 units" rescale image by: 50/83.6 = 0.598
  • "Modify / properties" and click the image (remember that you should have selected the right layer)
  • The property menu opens. Select entry "scale", change default value "1" by "0.598"
  • "Info / Polygon area" and click around on the picture. In the example we examined the size of the meadow.
  • The more points you click the more precise the measurement may be.

In our example we got an area of 7116 units^2. 1 unit = 10 m, so 1 unit^2 = 100m^2.
7116 units^2 == 7116 * 100 m^2 = 711600m2 = 70 ha.
Quick control: the longer size of the rectangle has a size of about 1000m, the shorter of more than 500 m, why 70 ha should be in the right dimension.

Rescaled image