How to fit the coastline to the mesh?

General discussion about Scenery Design. Questions about SBuilder for Flight Simulator FS2004.
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Mick
Posts: 59
Joined: Fri Oct 05, 2007 7:42 pm
Location: Germany

How to fit the coastline to the mesh?

Post by Mick » Thu May 08, 2008 12:31 pm

Hello everybody,

even after a lot of positive experiments with SBuilder I'm still struggling with coastlines and would really appreciate if anyone could inspire me with the right techniques for doing this... (SB 2.5.06 / FS9)

Here's what I do and where the problem arises:
1. I create the mesh for my region (works fine and looks good in FS)
2. I use a background bmp from Google Earth (or FS birdseye) and paint my new coastline with VTP lines, assign a custom layer for them (so that I can exclude the default layer 8 afterwards) and the other VTP properties.
3. I create the LWM mask with all the different LWM polys
4. I make the bgls, install the scenery in FS and check if I need any additional area fills (my region is quite shifted in the default FS)
5. As a result, I basically have a new coastline. Unfortunately it's a huge amount of work and in the end doesn't fit in several ways.

The following problems arise:
a) Step 3 is really hard, and I don't know if there's no advanced technique to make that easier. As far as I read I'm supposed to have a single poly for every cell. Fitting each poly to the relevant VTP line is made a bit easier with the "Make Poly" command, but since the lines are usually longer they cover more cells and I have to split each and every poly individually.
b) When doing this, the next difficulty comes up: At which SB zoom level will I have to fit the polys? In the experiments it turned out that I have gaps in the surface when I don't at least fit the polys to the grid (i.e. offside the VTP line)at zoom 512 or even 1024. Is there any hidden command like "snap to grid"?
c) How does the wrong or right way of doing all this affect my frame rate? It seems that through some intermediate checks I have significantly higher frame rates, and I'm confused about how to reach this positive effect purposely?
d) Most important: In the end result, the VTP lines and polys might fit together after hours and hours, but the visual coast doesn't fit the mesh! That's really frustrating... In my scenery I e.g. have a VOR standing right on top of a cliff (I use the airport flatten for that), but it seems impossible to make the cliff steep enough that the water and the VTP coastline don't climb up (see next).
e) In some places the water and coastline even climbs up the mesh! I studied all the available tutorials, checked every LWM poly to have altitude 0... but still. Any idea what could be wrong with that?

Thanks for your ideas on that,
kind regards
Mick

scott967
Posts: 67
Joined: Wed Oct 06, 2004 5:08 am
Location: O'ahu Hawai'i

Post by scott967 » Fri May 09, 2008 1:46 am

I think that is the core problem with this approach. I recently did some scenery of an airport situated on the SW coast of Korea, and did some coastline. As you say, it is hard to get mesh coastline and water poly to all agree. Using a wider coastline can help cover up errors. There were a couple of programs which were intended to generate coastlines. These are slartibartfast and autoasm. I never got too far with them but they might have some ability for you. Something I have done with different degrees of success is use some commercial GIS software that could create contour lines which could be used for a coastline. It works better when the mesh is somewhat steep. Low lying areas can create a mess of the contours. If you are using SRTM mesh, it just doesn't work because the resolution isn't good (though if you had a good smoothing method you could maybe fudge it to look better).

As far as I can tell, cliff-climbing water is almost impossible to prevent.

scott s.
.

Mick
Posts: 59
Joined: Fri Oct 05, 2007 7:42 pm
Location: Germany

Post by Mick » Fri May 09, 2008 8:59 am

Thank you, scott. Maybe you show me up the limitations here, especially since I used SRTM mesh for my scenery... I had also tried around a bit with slarti and autoasm and didn't get too far with them - I guess you have to be a professional to even fully understand how to use them. So my temporary solution is the same you recommend: making the coastline wider.

From all the theory I studied by now, my flatten poly (airport level 150 ft) should keep the mesh up, while the water LWM polys (sea level 0) should "press" it down, so that the distance would just have to form the cliff. That's why I don't really understand the results we're both facing.

Does anyone else have better experience or explanation? What's wrong about my understanding of all the theory? And would there be any way to save some work with the fitting of the dozens of polys?

Thanks again
Mick

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