[mapguide-users] Map scales inaccurate by %13.528

[Traian Stanev]

If the map is rendered in degrees (which seems to be the case based on the status line text), then the map scale is only accurate for either the vertical or horizontal dimension. Sheboygan being at the latitude it is, one horizontal degree is probably half the distance of a vertical degree. So it makes sense that if the scale is based on vertical degrees (which is more likely given they vary less in length), then a diagonal line will be less than what you expect from the scale value.

Try drawing a vertical line to verify if this is the case.

Traian


________________________________
From: mapguide-users-bounces at lists.osgeo.org [mapguide-users-bounces at lists.osgeo.org] on behalf of Berg, James [James.Berg at stantec.com]
Sent: Wednesday, October 08, 2014 8:46 AM
To: mapguide-users at lists.osgeo.org
Subject: [mapguide-users] Map scales inaccurate by %13.528

MapGuide Open Source 2.5.2
Windows Server 2008 64-bit

It looks to me like map scales are inaccurate. According to my calculations they’re off by %13.528.

Here’s how to demonstrate the inaccuracy:

Open localhost/mapguide/dotnetsamples/main.aspx

Zoom to scale 1:1000

Draw a line that is one foot long using the measure tool.

The measurement of the line according to the task pane is 0.14 miles. If this is converted to feet that’s about 7392 feet.

Since the current zoom scale is 1:1000 you would expect a foot long measure redline to be 1000 feet, not 7392.

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