FS2004 Compiling the Ground Polys

Hi all, just another couple of questions related the GP poly compilation.
For FS2004, using last ADE version available and last ADE_GroundPolys.dll version (2.2.19) in the final part of the compilation appears the Compile Parameters dialog box. Local Elevation, Full visibility is selected by default. Now reading ADE-GP user manual it reports:
Single Ref. Point, Local Elevation, Full Visibility- compiles all ground poly objects
using the elevation of the ground for reference. This is the default for P3Dv3 and for
FSX when materials have been used. For other situations, if the ground poly objects
are at other than ARP elevation, use this option.
But I don't understand how the poly could be at a different elevation other that ARP because I don't see any parameter in the ADE-Gp Poly editor. Anyway is "Local Elevation, Full visibility" selected by default because it could be better that using "ARP Elevation, Full Visibility" or not?

Other question related to the line visibility (or poly visibility following the different situations).
I'm not sure to have correctly understood the word "processed" in the user manual. this is the "culprit" part of the manual:
If, at some point, the lines are too far away to be
rendered in a meaningful fashion, processing resources are being wasted which
adversely affects FPS. This entry allows you to specify the distance (in metres)
beyond which the lines are not processed.
I tried to compile one time using full visibility, and another time using line visibility set to 5m (probably is too short but I did it to see the result unequivocally, provided I understood how the option works), but except for the little bigger dimension of the result bgl file, I did not see any difference.
So what does it mean the word "processed"? Could you please explain me better?


Resource contributor

"Local Elevation" means just that - the GP polygon is placed at the elevation at the GP's location, instead of the ARP elevation.

"Processed" means "displayed". So the lines are not displayed beyond that distance. I think 5 m is way too short a distance to be actually used by FS. There is probably a minimum distance?
Hi Andrea:

AFAIK, in order for a G-Poly to be visible, it must be displayed on top of any other layers at ex: an airport.

If the FS2004 ARP Altitude is known, the G-Poly can (should ?) be assigned that same Altitude AMSL (aka elevation AMSL).

The VTP layer number, which must also be assigned to a G-Poly, determines whether it is visible on top of any other layers at ex: an airport.

I believe you might find FS9 G-Poly creation easier to implement using Arno's MCX G-Poly Wizard. :idea:


Some videos on this topic:


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Resource contributor
Hi Andrea. Tom has answered your first question, FS8-style GPs are drawn at ground elevation - whatever it is. Any GPs off the flattened surface (which presumably is at ARP elevation) could be at other than ARP elevation.

Re your second question, i.e., "processed" in the context of line visibility, the focus of line and poly visibility is processing efficiency, i.e.., minimal FPS impact. GPs are partitioned into QMID15 cells - which, I recall, are 1.2km squares. If any portion of a QMID15 cell is within the specified visibility distance, ALL the GPS (or portions thereof) in that cell are drawn. So, with a 5m visibility setting, you would see everything in the QMID cell that contains the user aircraft. Consequently, you should consider visibility settings as meaning minimum visibility.

While 1.2km squares may seem large, even a medium sized airport could extend over 6-9 QMID 15 cells and even a few more on the fringe. So the feature can potentially offer very significant efficiency improvements, particularly where there are a lot of small polys and/or short lines that are visible only from a short distance.

Sorry Don for late further answer to your last post. After it, the question is a little bit more clear, but I’m not sure it’s clear at all.
So the QMID15 cell should be a square of about 1,09km per side. Then if I stay in the center of it I have about 505m of range till the end of the square.
Now let say that I use 250m visibility setting in the last windows of the compile process, if I'm in the center of the cell, as you said, I should be able to see all the polys of the cell till its limit and nothing related to polys falling in the adjacent cells, if I stay 100m from the cell limit, I will be able to see polys of the adjacent cell because it is inside the visibility limit. Is this correct?
If so, I also understand that I have to pay attention to this because the visibility of the lines could be correctly reduced using this option, but the same could be not correctly said for ground polygons like taxiway or runway that could disappear above a certain distance.
Tell me if I'm starting to understand the potentiality of this option.



Resource contributor
Andrea, your initial question related to you seeing polys/lines beyond the specified visibility distance. I responded:
If any portion of a QMID15 cell is within the specified visibility distance, ALL the GPS (or portions thereof) in that cell are drawn. So, with a 5m visibility setting, you would see everything in the QMID cell that contains the user aircraft. Consequently, you should consider visibility settings as meaning minimum visibility.
The portion of your post above starting "Now let say …" indicates you have understood that correctly. It's not clear what you are asking in your final question since taxiways and runways are not drawn as ADE-GPs.

Yes Don, maybe I did not explain clearly what I meant.
I thought that reduce the visibility (so stop drawing) of lines with distance it’s a good thing because also in the real world the lines painted could became more or less invisible after a certain distance from the observer. The same thing could not be true thinking about asphalt for example because the runway strip is visible from very long distance so it should not be included in a compiled file with the above option active.
it was probably just twisted reasoning to test if I correctly understood the working policy of this option.

Anyway I made a test drawing 3 different gp polys on the runway at 250, 500 and 1200 m from the starting point of the airport (on the same runway). I compiled them using 250m in the option.
I started FS9 and I went to the starting point. All the three polys were visible. I started moving back away from them but I noted no differences. They remained visible even if I was 3/4 nm distant from the runway. So I suspect I did not understand something about this option.


Resource contributor
Actually, the feature is intended to reduce FPS-hit by not drawing GPs more than a certain distance away (plus block size). (But your explanation works as well, Andrea.)

It's possible that, during the evolution of ADE-GP I have done something that has "broken" the feature.

I'll check it out when I get a chance, primarily to answer your question. But, if it no longer works and the cause is not simple and isolated, it's going to have to stay broken. Messing about in that area of the code is likely to "break" something else.