Hi Josh
From: Josh Babcock <[EMAIL PROTECTED]>
dene maxwell wrote:
> Hi Josh
> I posted on this subject a couple of weeks ago.... there was some
> discussion as to where the "scaling" of the texture was done
> Terragear/FlightGear. There were two points;
>
> 1) ... when viewed from above a 45deg slope will only seem 0.7071 of its
> true length. Hence a "stretching" issue when viewed from the side.
>
I was thinking more of stuff between 70 and 90 deg, places that are
steeper than the angle of repose and would never have trees, let alone
soil on them. This foreshortening is exactly what happens in real life
when you look down at a cliff, and it would be appropriate to see the
same in FG. In fact, the current situation that we currently experience
in steep areas is a very exaggerated version of the problem that you
describe.
True, the steeper the slope, the more exaggerated the problem. Do you agree
there are two issues, the stretching and the appropriateness of the face
material (ie does your comment " irrigated fields stretched up a hillside"
recognise both issues ro do you see them as one in the same thing?)
> 2) ... the current terrain is designed to be seen from above... When
> viewing terrain from the side other factors come into play...your
> stratum idea and the one I put forward where urban terrain is presently
> designed from a "birds eye view" ie roof's, when this is viewed from the
> side it should be walls and windows, the roofs always being on the
> uphill side. This implies left and right handed scenery amongst other
> perspective issues.
>
Personally, I like to fly in mountainous areas, .....
my landings need too much practice to skive off and enjoy the scenery <g>
.....and I often find myself
looking sideways at a cliff. Again, I am not talking about flat terrain,
but vertical terrain. It really ruins the illusion when can look
sideways at an irrigated field that has been stretched up the mountainside.
My point is that perhaps some of the terrain should be designed to be
viewed from the side, and not above. The trick is teaching terragear to
determine what that terrain is and assign it a new landcover type: cliff.
.. Agreed; cliff, "right" hilly urban and "left" hilly urban. I'm sure
others will come up with other landcover types.
It would be nice if Terragear was able to this automatically, as an interim
solution, if the landcover types were available in FGSD users could
customise areas that they want. Is it hard to add landcover types? Are there
any other issues that I'm not aware of?
Since a picture is worth a thousand words, here's two thousand:
http://jrbabcock.home.comcast.net/flightgear/one.jpg
http://jrbabcock.home.comcast.net/flightgear/two.jpg
I think your pics beautifly summarise all the words written on this subject.
> Sort of associated with your river issue is the issue of railways and
> the sections of railways that are through tunnels.... this particularly
> effects me as two of the longest rail tunnels in the southern hemisphere
> are in my local area and it looks silly to have them placed on the
> surface climbing 60deg slopes .... I have talked to Fred about being
> able to resolve this in FGSD but no firm answer yet.
The first step would be to find a dataset that shows where the linear
features are not on the surface. This is the same issue as with bridges.
If we can find a dataset that represents this like topographic maps do,
it will be a piece of cake to have automatically generated bridges and
tunnels.
That would be great.
Josh
>
> Cheers
> Dene
>
>> From: Josh Babcock <[EMAIL PROTECTED]>
>>
>> I. Currently the terrain textures are UV mapped onto the terrain from
>> directly above. This creates all sorts of problems in steep terrain.
One
>> of those problems is that cliffs and near cliffs look really bad.
>> Perhaps if terrain with a slope greater than a certain threshold were
to
>> be mapped from the side with a texture bearing strata this particular
>> case would start to look right. What would be involved in making
>> particular terrain types be mapped differently?
>>
>> II. Another thing I have been thinking about since the new scenery was
>> released is flattening rivers. The new algorithm certainly makes places
>> like the Grand Canyon look a lot more like they should, but there are
>> still a lot of rivers that travel up and down like roller coasters.
>> Perhaps if once the linear database is in sync with the elevation data
>> it would be a good idea to tell the algorithm where the rivers are so
it
>> can increase the number of vertecies along the rivers. On the other
>> hand, maybe simply getting the linear feature data in the same place as
>> the elevation data will be all that it takes.
>>
>> A really smart algorithm would also be able to see when it is laying
>> down a river on a slope and move it to the bottom of the valley. It
>> might even be able to figure out the registration error between the two
>> datasets this way and automatically adjust for that.
>>
>> Josh
>
>
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