FSX Effects in wrong place?

arno

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#21
Hi,

OK, I finally had some time to look at this issue. I made a simple test object with 3 attached effects on a row at 250 meter apart. And indeed the light effect I put at the top get's an offset the further you go from the reference point. At 500 meter distance the offset was about 0.7 meter.

So I had a look at the difference in coordinates you would get if you calculate with the old flat earth and the new curve earth formula's. And the difference is 0.7 meter!

It seems my guess before was wrong btw. From the coordinates I calculated now it seems that the effect has been correct for the new curved earth, while the object itself has not.

I think I can add a function to ModelConverterX to correct this offset again, but my question would be how would this fit into the work flow?

  • Be able to load the MDL in ModelConverterX, start the correct function and export the MDL again?
  • Have a tool to tell you which coordinates to use so that you can place the effect at the right location in GMax?

Let me know what you think and then I can probably add the function quite quickly.
 
#22
Are you planning to correct the object vertices/polys or match the effects with error of the objects?
The first thing would be better cause then we can place objects more correct in FSX, if you would correct the effect then we still would have an offset with other geometry/objects and also arial images. Espacial the offset in the length would be not so cool.

My choice would be version A, the loading in MCX and then exporting it with the correction
 
#23
Hi Arno,

My choice would be A as well, so that I can reuse the Gmax file when I port my scenery back to FS9 without the need to move the effects back again.

Cheers

Phil
 

arno

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#24
Hi,

Good question which way we need to correct. I want to run a little more tests on it.

Initially I was thinking to move the effects to match the geometry again, since usually people will look more at the geometry. But it would also make sense to correct the other way around.

Maybe I can make it an option so that you can do both :). For the math involved it would not matter that much anyway.
 
#25
Hi Arno,

I've just re-read your previous posts and have had time to digest what you said.

If the effects are being correctly placed based on the curved earth is it the case that all FSX 3D objects are actually scaled very slightly wrong, not an issue with small buildings etc, but more of a problem with large terminals, hangars,etc?

If this is the case then I guess the geometry should be corrected to make it accurate...although having both options might benefit others if you can make it :)

Cheers

Phil
 

arno

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#26
Hi Phil,

I will do more testing tomorrow. It is indeed a bit scary if all geometry would be a little wrong. So I want to double check which one is correct.
 

arno

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#27
Hi,

I have done some more testing. Let me explain what I did.

Like I described in the previous post I made some boxes with a attachpoint of a light effect on top. I put three of those in a row, with 250 meter distance.

And I made a seperate thin needle object as a reference object. I placed this reference object at the coordinates I would expect each of the boxes to be (using the same flat earth to geodetic formula's that we always used in the FS2004 days).

Attached you see an image of the result. It shows the box the furthest from the reference point. As you can see the light is displaced from the geometry. But it lines up exactly with the thin reference object I added.

So which one is wrong?

If you assume that you are still modelling in the flat earth coordinate system that we always used, then the box (geometry) is wrong. The light and matches with the reference object.

If you assume that you are modelling in geocentric coordinates as used by the FSX curved earth, well then the geometry is right and the light would have an offset.

So I guess which one is right or wrong really depends on your assumptions when you started modelling.

I guess as a correction it would be useful to be do the correction in both directions, based on what you want.
 

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#28
Hi Arno,

So if I understand correctly, what we're actually seeing is the FSX engine using earth curvature calculations to draw 3D objects, but using flat earth modelling to draw the effects, even if they are contained in the same mdl?

If this is the case, I would prefer to move the effect so that it is in the same lat/lon position in FSX as it would be if the same mdl is compiled and used in FS9 (which I will be doing when I port the scenery back).

As you say, others may want the other way, so giving both options would be best, if possible.

Cheers

Phil
 

arno

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#29
Hi Phil,

Yes, that is correct. It is weird that they choose to render them differently.

To get effects at the same lat/lon if you export to FS2004 and FSX, you would have to move the geometry, not the effect :).

But this all get's quite confusing, since it is hard to say what the reference really is. We are quite used that XYZ coordinates from GMax behave in a different way, but actually they behave differently in FSX.

I think at first I can only add a function to correct the attachpoints. To do the reverse I need to implement a geocentric XYZ to lat/lon function first, which I don't have at the moment. I do plan to add that later, but that will take a little more time.

Besides that the correction also depends on the location where you place the MDL. So to be able to correct it I need to ask the user to enter the lat/lon of placement.

Argh, it would have been much easier if FSX just used one coordinate system for everything.
 

arno

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#30
Hi,

I have added the function to ModelConverterX now, so from tomorrow it is in the development release. Here is a quick "manual" for it.

You will find it in the "Special tools" menu, there is an entry "Correct effect placement to geometry (FSX)". But before you run this function you need to make sure the object placement is specified in the Object Information form. After running the function just expect to MDL again and things should be fine.
 
#31
Hi Arno,

Fantastic, I'll download tomorrow and do some testing for you and report back.

I can see that the other option is more complicated but will be ready to test when you get some time to implement it. Just let me know when :)

Thanks

Phil
 

arno

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#32
Hi Phil,

I want to implement it in the future as well, it is just that I don't have the conversion formula's in the tool yet. For the conversion implemented now I had all math available already :).
 
#33
Hi Arno:

I'm trying to better understand the implications of this discussion, with a goal of at least identifying what projection my background imagery should be in (for "best and/or easiest" results) when I model in Sketchup (...or GMAX / 3DSMAX): Geographic LAT-LON WGS84... or "Flat Earth". :banghead:


Perhaps you could explain a bit more what you are referring to when you use the term "geocentric" in the context of Sketchup (...or GMAX / 3DSMAX) modeling in that 3D world environment ? :confused:


My goal is also to identify what we may be able to do (if anything) while still inside the Sketchup (...or GMAX / 3DSMAX) environment to make a model as ready as it can be for proper display in FS... before actually importing to FS via ModelConverterX (aka "MCX")


But certainly we all sincerely appreciate having MCX available as a portal to FS, and even more-so, to have tool features in MCX to help us work around the quirks of FS content creation, import, and display. ;)

[EDITED]

Could you please elaborate on this subject of "Geographic LAT-LON WGS84" versus "Flat Earth" projection versus "geocentric" ...as it pertains to modeling in the 3D world environment of Sketchup or GMAX / 3DSMAX ? :eek:

[END_EDIT]

Many thanks in advance for sharing some additional insights on this situation. :)

GaryGB
 
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arno

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#34
Hi Gary,

I plan to make a detailed post or tutorial about it. But it is all quite complex matter, so I need to consider how to explain it clearly :)
 
#35
Thanks Arno... I'm confident we'll see a carefully-considered treatise on the matter by you at some time in the future, just as you have so kindly done for us all before with many other topics. :)

GaryGB
 
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#36
Hi Arno,

I've just done a quick test and I'm not getting the desired results. In the attached screenshots the refpoint is approximately 30m to the right of the object. The first image shows the default fsx mdl, with the effect offset to the right (further from the refpoint than the geometry). The second image shows the altered mdl using the new mcx functionality. It has moved the effect back too far, the effect now being closer to the refpoint than the geometry.

I noticed that mcx (in the attached object editor) only positions attachpoints to 2 decimal places. Could this be the cause of the error, if both the initial position is rounded and the resulting position is also rounded there could be issues maybe?

Cheers

Phil
 

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#37
This is very interesting guys. I've posted a few times about this on the forum. What I was doing was using the multiple_boxes script to apply an effect to all my taxi lights in gmax and then exporting. The result was the same as I am reading here:the gmax model was in the right location but the effects was not and the deviation gets worst the further you go away from the ref point.

My solution was to split up my gmax scene into a number of files and export each around the red point. This is a "work around" but it would be great if there was a tool that compensated for this deviation.

Phil what have you used to try this out? Is there an option in mcx to allow for this deviation as I would like to give it a go. I've downloaded mcx from the tools section here but no option for "Correct effect placement to geometry (FSX)"

Terry
 
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arno

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#38
Hi Phil,

I'll double check it tonight. Are you sure you entered the right lat/lon for the object? With a wrong position entered the correction will also be wrong.
 

arno

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#39
Hi Terry,

You would need the latest development release for this. Check the sticky thread in the ModelConverterX forum for details.
 

arno

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#40
Hi Phil,

About the amount of decimal places, the attached object editor only shows a certain number, but internally the position is stored with double precision, so that should not be an issue at all.
 
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