Answered

BingMaps.GetMapV2 scale in m/px

(0) Share

Report

Posted on by FlorentGiboin

Hello,
I am creating an app with BingMaps.GetMapV2. I need to know how many meters represent 1 pixel.
I am using this article Understanding Scale and Resolution - Bing Maps | Microsoft Docs and apply my latitude correction.

BTW, when I check my result with google earth it's false.
Any idea ?

Categories:

Building Power Apps

I have the same question (0)

All responses (6)

Answers (1)

Sort by

BCLS776 8,994 Moderator on at

Like (1)

Report
Copy link

Link copied!

@FlorentGiboin wrote:

Hello,
I am creating an app with BingMaps.GetMapV2. I need to know how many meters represent 1 pixel.
I am using this article Understanding Scale and Resolution - Bing Maps | Microsoft Docs and apply my latitude correction.

BTW, when I check my result with google earth it's false.
Any idea ?

The document you quoted is a good resource - keep that around for a handy reference. One thing to note, some of the information it describes is based on the assumption the Earth is a perfect sphere. In reality, it is better represented by an ellipsoid, so the spherical assumption can carry some error along with it. However, that level of error isn't important to most people unless you need high precision over long distances.

First, tell us a bit more about your app and its purpose. Are you trying to calculate scale for some sort of precise positioning task, or is it to help your user understand what 50 metres or 20 kilometres looks like on the map? When you say you "check my result with google earth it's false", can you share more info? Is it giving you a slightly imprecise calculation, or is it grossly misstating what you believe is the true answer?

Seeing the code you are using so far can also help us spot any missteps.

Bryan

Was this reply helpful? Yes No
FlorentGiboin 29 on at

Like (0)

Report
Copy link

Link copied!
My goal is to let user select a point in the map then store the coordinate.

I am already able to let user select a point. And I am able to get pixel Y/X based on the center of image.
Without knowing the scale (meters/px) I can't determine point GPS coordinate. For my test, I use this formula

BingMaps.GetMapV2("Road",14,49.88125 ,2.31831,{mapSize:"1366,768",pushpinIconStyle:121,pushpinLatitude: 49.881121,pushpinLongitude: 2.284551})

Real distance is 2418.92 meters.
Number of pixel is -393 pixel.
Base on the documentation zoom 14, raw pixel 9.55, converted latitude 8.853675285

393 * 8.853 =3.479m
So there is a problem.

Was this reply helpful? Yes No
Verified answer

BCLS776 8,994 Moderator on at

Like (0)

Report
Copy link

Link copied!

I think the issue may be with how you are calculating the latitude correction. I found the cosine of 49.88 degrees to be 0.6444, which yields a resolution of 6.15m/pixel at that zoom level. 6.15 x 393 works out very close to the distance you measured in Google Earth.

If you are using a cosine function in Power Apps or Excel, its argument needs to be in radians and not degrees.

Hope that helps,

Bryan

Was this reply helpful? Yes No
FlorentGiboin 29 on at

Like (0)

Report
Copy link

Link copied!

Radian VS Degrees, it might be the answer ^^.
Thx a lot

Was this reply helpful? Yes No
FlorentGiboin 29 on at

Like (0)

Report
Copy link

Link copied!
With that collection it's working, once degree transformed in radian.
With({multi:Cos((Location.Latitude*Pi()/180))} ,ClearCollect(zoomLevel, {val:14, meters:9.55*multi}, {val:15, meters:4.78*multi}, {val:16, meters:2.39*multi}, {val:17, meters:1.19*multi}, {val:18, meters:0.6*multi}, {val:19, meters:0.3*multi}) );

Was this reply helpful? Yes No
rbrundritt 4 on at

Like (0)

Report
Copy link

Link copied!

Bing Maps uses a Mercator map projection with 256x256 pixel tiles. If you know the zoom level and the latitude value of the center of the map (or the point you are interested in) and calculate the distance in meters per pixel using the formula: `(cos(latitude * pi/180) * 2 * pi * 6378137) / (256 * 2^zoom)`. This is documented here as the ground resolution: Bing Maps Tile System - Bing Maps | Microsoft Learn

Was this reply helpful? Yes No