FSX About Landclass tile ground dimensions

Hi guys

Well, my question is included in the message tittle.
Whatever the landclass resolution is, up to 4096, I guess it covers the same surface on the ground, perhaps depending on the latitude.
So, I'd like to know more about this surface, say at a medium latitude of 45°, its value and/or how to determine it.
Thanks

JpP
 
Hello:

Indeed, land class "tiles" that texture the ground do vary in size and (rectangular) shape within the N,S,E,W-oriented QMID terrain grid vertices.

You may wish to review the following linked info for ideas on how the MSFS terrain system works, and how to better pre-determine (and calculate) the relationship between a texture source image size in pixels and what Geographic area that image will cover on the ground when "draped" onto the Quads and Area Points which make up the terrain mesh within the FS Quad Matrix of terrain 'tiles':


http://www.fsdeveloper.com/forum/threads/calculation-of-lat-lon-can-it-be-done.425018/

http://www.fsdeveloper.com/forum/threads/getting-coordinates-from-existing-bgl.435585

http://www.fsdeveloper.com/forum/threads/cvxextractor-exporting-vector-data.432918/page-3

http://www.fsdeveloper.com/forum/threads/sbuilderx-textured-polygon-showing-as-black.435733/#post-728251


Hope this helps ! :)

GaryGB
 
As always, thank you, Gary! Your willingness to help deserves. more than these two words (maybe 2 pints of your favorite beer) :) Although it sometimes takes me several days to fully understand your posts... My ignorance, that is.


Sent from my Galaxy S4 using Tapatalk
 
Hi guys

Well, my question is included in the message tittle.
Whatever the landclass resolution is, up to 4096, I guess it covers the same surface on the ground, perhaps depending on the latitude.
So, I'd like to know more about this surface, say at a medium latitude of 45°, its value and/or how to determine it.
Thanks

JpP
Hi again:

I finally located 2 references I was looking for in order to answer part of your opening post questions. :coffee:


According to MS Game Studios - ACES' team member Adam Szofran's wonderful article "Global Terrain Technology"

"we designed our quad tree so the ratio of north-south to east-west extent of the cells is nearly 1:1 at +/- 45 degrees of latitude."

http://www.avsim.com/topic/311168-fs9-autogen-issues/page-2


According to Arno, 41.41 degrees is the North Latitude at which Quad Matrix terrain grid quad tile size aspect ratio is closest to a 1:1 ratio:

"Due to the size of the autogen tile in degrees they correspond to a square area in meters at a latitude of 41.41 degrees."

http://www.scenerydesign.org/2014/05/autogen-object-distortion/


Hope this helps with your learning process ! :)

GaryGB
 
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