Making Photoscenery more realistic

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old grey dog
Posts: 25
Joined: Wed May 04, 2011 11:06 pm

Making Photoscenery more realistic

Post by old grey dog » Thu May 05, 2011 9:58 am

I have been using photoscenery quite extensively initially with purchased products and lately with aerial/satellite photos I have loaded through SBuilderX.

The terrain meshs on which the photos are draped (I've got Global 2010 loaded) appears to be the underlying ground levels (discarding buildings and other protruding features). It has occured to me that modifying the mesh with perhaps flattening polygons with elevations applied to the various points, where there are building or forests say, would improve the 3D effect when flying close to the ground. I presume this would impose less processing overhead than placing building/tree objects particularly in an urban/semi-urban setting.

My initial thought is that some sort of toolkit could be developed which would have primitive shapes that you could place like building objects but which work by finding the terrain ground level at the placement point and contructing, say, a house shaped protrusion up from the terrain at the position where a house appears on the photoscenery. The photoscenery would then drape over that.

I don't know if I'm explaining myself very well and apologise for my long winded post.

Has anyone else got any thoughts on this?

Wally-Bob
Posts: 13
Joined: Sun Nov 08, 2009 6:25 pm
Location: Baghdad, IRAQ

Re: Making Photoscenery more realistic

Post by Wally-Bob » Sat May 14, 2011 6:02 pm

Old Grey Dog,

I get the idea of what you are trying to do. A couple of things here, negatives. The flatten polys interact with the mesh terrain and places (tessellates) a slope from the edge of your poly to the nearest node (pixel) of the mesh terrain, some times with unexpected results. Depending on where in the world you are referring, the vast majority of the world is available in FSGlobal 2010 at 75m. (Hawaii & So. California @ 10m) Thus the "native" building size would be 75 meters by 75 meters, and would have a sloping edge to the next pixel 75 meters away. The photoscenery would then drape over this tetrahedron, but since only the roof top is usually seen in the photo the result will not resemble a house. Try it, there is always value in an exercise because you will come away with a better understanding of what is happening within FSX. You will quickly see that this is not the preferred method from an aesthetics and ease of design point of view.

The rule of thumb is the more complex (scenery object density), the longer the processing time.

wally-bob

old grey dog
Posts: 25
Joined: Wed May 04, 2011 11:06 pm

Re: Making Photoscenery more realistic

Post by old grey dog » Mon May 16, 2011 12:44 pm

I had wondered about that as an issue. What you have said would explain some of the somewhat strange effects I have seen so far.

I think that there is a possible solution. If trying to represent a simple rectangular building, say, this could be done by first flattening at "ground" level (ie. the level defined by the surrounding mesh points) with a rectangular area just slightly bigger than the ground plan of the building. Then superimpose the rectangle representing the roof level. This should avoid unpleasant slopes to nearest mesh points.

Wally-Bob
Posts: 13
Joined: Sun Nov 08, 2009 6:25 pm
Location: Baghdad, IRAQ

Re: Making Photoscenery more realistic

Post by Wally-Bob » Mon May 23, 2011 9:18 pm

Old Grey Dog,

Nope, unpleasant/unexpected results will occur. Pretty much if you want a building, you need to place one.

If you draw a line at an angle in CAD for example, even though it is a straight line (in analog) it will appear to be a staircase at the resolution of the monitor. (in digital) FSX is digital, uses pixels. For mesh the flatten poly edge will be at an angle but the elevation data points will only be noted on the mesh grid nodes (pixels) as determined by the mesh resolution slider. The grid runs true N-S and true E-W. Placing two flatten polys at an angle having one apparent edge in common in a top down view at different elevations will be rendered in FSX as a jagged line following the mesh grid approximating the angled straight line. 45 deg = over one-up one. 30 deg = over two-up one and so on ...

Flatten ploys are intended for "Large" areas. Large is a term relative to the resolution of the mesh terrain grid. In engineering/physics terms, a metal window screen will reflect Radar as holes in the surface are well below the order of magnitude of Radar wave length. It will pass light as holes are well above the order of magnitude of wave length. A building is on the order of FSX mesh resolution.

Wally-Bob

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