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I am working with QGIS 1.8 and 2.6 and can't get any of the Cross Section Profile tools to provide the ellipsoid ("proper") distances. All the distances use geographic coordinates which are too long/far.

For example, the straight line distance from Vancouver BC, to Kelowna is about 270km. My cross sections all say it is 420km.

The QGIS distance measurement tool allows you to use the Ellipsoid (I set mine to WGS 84) and give me 271km.

Can anyone shed light on how to get any of the profile tools to give me the "proper" distance?

Measurement give correct distance

Plugin 1 gives incorrect 4.0?

Plugin 2 gives incorrect 400000? So did number 3

  • hey fellow BC'er. Can you try it with the DEM projected to BC Albers or with OTF projection turned on to that? – SaultDon Nov 13 '17 at 4:51
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As a land surveyor I go straight to the source of mathematical projections and transformations. Corpscon 6.0 allows the user to convert coordinates between Geographic, State Plane, Universal Transverse Mercator (UTM) and US National Grid

You can simply type in the coordinates of your existing Projection (Angular) and set output answer to a Cartesian Coordinate (i.e. Universal Transverse Mercator). Put both of your derived UTM coordinates and measure between them. Just a note: WGS84 (Angular) and NAD83 are based on the same elipsoid so they are essentially the same system. A Google Search will find Corpscon but it was written and adopted by the U.S. Army Corps of Engineers. You will have to change your projection to UTM in your GIS program bit I usually make a separate GIS Layer with the Cartesian (NAD83) to measure these. That way I am not taking any chances with my original drawing.

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For "metric" measurements (which your distance axis is) it is better to use an equal-area projection like [LAEA EPSG:3575]. You could reproject your DEM using gdalwarp and wor on your profiles.

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