Sign in to follow this  
Guest

Flying Trees !

Recommended Posts

Hello scenery designers wizards !You could have certainly sometimes observed autogen flying trees in FS2002.Can someone can be kind enough to explain why ? Is it related to third party meshs or due to a lack of the computer memory ?ThanksTony

Share this post


Link to post
Share on other sites
Help AVSIM continue to serve you!
Please donate today!

My understanding is that it's third-party meshes. The problem would seem to be that the autogen expects the ground to be at a certain level -- the level of the default terrain. When a third-party mesh puts the ground level lower than that of the default terrain the trees just stay up at their original altitude, creating the floating effect. It's most disconcerting, I agree. I hope it's fixed in CoF.

Share this post


Link to post
Share on other sites

Hello Billthanks for your input, It happens indeed with 3rd party meshs but not only in my case (default scenery), that is why I think it might be due do a lack of RAMTony

Share this post


Link to post
Share on other sites

My only other informed guess then would be that you aren't seeing the most detailed LOD, and are seeing instead the lower-res terrain which might be more averaged in terms of altitude and therefore might result in floating trees. This could indeed be a RAM issue. What are your system specs?

Share this post


Link to post
Share on other sites

hello bill I have :AMD 1.5 ghz384 Ramge force 2 64 Mb !:-)

Share this post


Link to post
Share on other sites

After some experimentation last year, my best guess on the floating houses and trees problem is this:FS2002 uses the mesh scenery to decide what altitude to display each autogen object. Unfortunately, it uses the scenery in its most complex form to calculate the elevations, rather than taking account of the user's Terrain Mesh Complexity setting in Display Settings.When a value of Terrain Mesh Complexity of less than 100% is used, the elevations FS2002 uses may vary visibly from the 100% value. Typically it works out that the height is less than the 100% complexity height. Because the autogen objects are using the 100% complexity value, they are then left floating above the terrain.If possible, you should set your Terrain Mesh Complexity to 100%. Most users should be able to do this without any serious frame rate hit, except perhaps when using a high LOD mesh in areas of complex terrain.Even with the terrain mesh complexity slider at 100% there's a small amount of floating, but you have to look very hard to see it. It looks like the autogen is interpreting the mesh data slightly differently to the terrain renderer, but by using 100% Terrain Mesh Complexity, the anomaly is minimised.John FarrieVisual Flightwww.visualflight.co.uk

Share this post


Link to post
Share on other sites

Hello John,Interesting theory and worth further investigation, but I suspect system/sim performance is the primary cause.If your theory is correct, then it should be easy to test.* Set the Terrain Mesh Complexity slider to 0%. * Somehow force the sim to produce floating houses and trees.* Pause the sim* Force a screen redraw, either by restarting the sim or going into the Scenery Library and clicking "OK"If the elements are still suspended, you may be correct, but if the elements are now at their correct elevations, then performance is probably the real issue, since the same elevation data is still being used. (I believe this has always solved the problem for me.)Further musings:>FS2002 uses the mesh scenery to decide what altitude to display each >autogen object. Unfortunately, it uses the scenery in its most complex >form to calculate the elevations, rather than taking account of the >user's Terrain Mesh Complexity setting in Display Settings.I wonder what data it really is using. With high resolution mesh, there is a significant improvement in detail when the TERRAIN_MAX_VERTEX_LEVEL setting is increased to 21. This shows that the sim was not using all the information available, even if your Terrain Mesh Complexity slider is set to 100%. (And may not be even now.)I suspect the TMVL setting establishes the maximum level of elevation detail possible, and the Terrain Mesh Complexity slider allows us to fine tune (reduce) that detail as desired while flying.The sim uses the elevation data to construct polygons whose vertices are used to position the visible terrain textures. I assume it uses some form of CLOD algorithm to aggregate these data values to produce fewer and fewer polygons as the rendering extends to the horizon, where a single pixel may represent many elevation values.So, the "apparent" elevation of any location in the sim depends on the TMVL setting, the Terrain Mesh Complexity setting, and where that location is being rendered - from foreground (higher accuracy) to horizon (lower accuracy). Now, where do we place the autogen objects?This situation is most troublesome with high LOD data in areas where there is a large difference in elevation between the default and the addon mesh. With this much going on, in each frame, I have to expect that system performance remains a significant factor. The calculations are not being performed fast enough, and the autogen elements are positioned (apparently permanently, when they come into some visible range) at some intermediate elevation, while more accurate mesh calculations and rendering continue as you move ahead.Regards,Stevewww.fs-traveler.com

Share this post


Link to post
Share on other sites

Hi all.I think the floating autogen problem is just that... an autogen problem. I've had it with the default mesh... I've altered the FS2002.cfg file... I've played with the mesh sliders. No difference I could tell.But, if I go to the display screen, and turn the autogen slider to the left ( off ), reenter the sim, go back to the displayscreen and turn autogen fully to the right ( extreme density )... then on reentering the flight, the autogen is corrected, and seems to stay corrected. In fact, just turning autogen down a notch , then back up, seems to work as well.If you look at the "loading" alert, it starts with the "Loading 3D objects..." That's the autogen reloading.My guess is that it is a timing error, in the loading of the autogen. The autogen starts loading after the mesh is loaded, but before the mesh is done establishing the AGL. Slower computers would exaggerate the problem, and so would higher LOD meshes.There are other autogen bugs that plague designers, during the design phase. Where autogen disappears, and won't return unless we restart the sim... I'm thinking now, we could just turn autogen off, then back on.Attached is a FLT file ( as a text file ) use the browser's "Save Target As" and download... rename as "autogentest.flt", and place it in the "C:Program FilesMicrosoft GamesFS2002flightsmyflts" folder. You should see the folowing view:Dick

Share this post


Link to post
Share on other sites

Dick is exactly right. It really boils down to the system being able to load the terrain fast enough, the more power you have the less a problem this is, it really is as simple as that and of course 3rd party meshes take even more power or time to load because of the detail involved so the problem manifest itself even earlier than stock meshes, nothing to be alarmed about.Paul.

Share this post


Link to post
Share on other sites

Hi Paul.I think you stated it well. I'm doing an upgrade this week. New Asus A7N8x Deluxe motherboard, 1Gb DDR333 PC-2700 memory, AMD 2400xp+. ( from a Gigabyte 7ZXE, 640Mb PC-133, AMD 1600xp+ )This may be enough speed to eliminate the floating autogen in the above example. If it does, it can lay to rest the floating autogen question. I should be upgraded on Wednesday.Dick

Share this post


Link to post
Share on other sites

Here is a (probably rare) screenshot of floating autogen in the making.http://ftp.avsim.com/dcforum/User_files/3e6c935d32ce8fea.jpgAs you can see, autogen trees have been drawn well off into the distance on the base mesh. The inevitable result:http://ftp.avsim.com/dcforum/User_files/3e6c933e3281af66.jpgFirst, a bit of terminology. The term "default mesh" is not precise enough for this discussion. I use the term here to refer to the mesh we see in the foreground with the default FS2002 installation. This is usually MS-provided addon mesh in most areas and behaves no differently from other addon mesh. In particular, we can deactivate this mesh as well. I use "base mesh" to refer to the mesh we see at the horizon. I presume this is the dem4km.bgl data. The sim does not seem willing to start without this data.And an asumption. The rendered radius of mesh is inversely proportional to the LOD. I have demontreated this effect with LOD10-LOD13 mesh and the base mesh is visible to the horizon, so it it reasonable to assume this holds true for all intermediate LOD values as well.So, as we fly forward, the circle of higher resolution mesh moves ahead, "replacing" lower res mesh that was rendered in the distance. One cause of floating trees stems from the fact that some of the autogen elements are rendered at the elevation of the next lower res mesh, and do not move when the terrain is updated with higher res data as we move closer.This can often be demonstrated by taking a screenshot of the floating trees, deactivating the highest res mesh which is active (possibly the "default mesh" from MS), and taking another screenshot. Those suspended trees now usually lie on the next lower res mesh where they belong. And of course if you force the screen to redraw instead, they will be rendered at the correct high res elevation.This shot was taken in NY state, with only 10m LOD12 mesh and the base MS mesh active. This means there are often extreme differences in the elevations, and the sim can sometimes be caught at an intermediate stage where the smoothed transition between them has not been completed. The high res mesh here has an LOD of 12 so its effective radius is only about 6-7 miles, bringing the transition zone close enough for us to see these problems when they occur. These cliffs can last for just a second or two, and in extreme cases can fill much of the screen, flashing in and out of view very quickly. Quite a show.I chose the area because I can test with 10m, 30m, 100m, and 1000m data as well as the mesh from MS. With all available mesh active there seems to be a slight (<10%) degradation in FPS, suggesting that at least some of the additional files are being used. Having higher res data as a backup does not seem to help eliminate (nor aggravate) the floating tree problem, but does reduce their distance from the terrain. I tried several combinations with no obvious differences in results, other than elimination of the transient cliffs.Higher performance systems should help with this version of the problem. I suspect it will not help with the curious example Dick has provided. Those trees disappear if you fly over to them, but do not go away if the screen is forced to redraw. This suggests a problem other than performance. A very different problem! In the tradition of Taxonomy, Dick, you may have earned the right to name that particular "bug".Steve

Share this post


Link to post
Share on other sites

Hey Steve,Obviously there are a number of cases in which flying trees appear, but I eliminated my floating trees/cliff problems by following a suggestion you posted a few months ago (maybe around Christmas?).I regenerated my 10M scenery at LOD10, which paid off handsomely in several respects. First of all, it eliminated the floating autogen trees. Secondly, it smoothed out several cliffs around the default coastline and around a default airstrip. Finally, it greatly reduced the mesh filesize while providing detail that is visually nearly indistinguishible from the LOD12 scenery, and allowing me to leave the TMV set at 19. I'm now a firm believer that LOD10 is the best compromise for including maximum detail while still blending in with the default scenery. I'll try and post some screenshots in the Mesh forum later. I've been meaning to post on the subject for a while, since you asked for confirmation of the results, but work has kept me from serious scenery development for a while. Anyway, thanks for the tip!andy

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this