Sign in to follow this  
rhumbaflappy

LOD Grid Lines and Locations...

Recommended Posts

Can anyone give me a formula for precisely determining LOD grid lines in Latitudes and Longitudes, any level? I realized that I was calculating something wrong in my GMAX LOD Tool... but I don't quite understand where I went wrong. I thought that at LOD0, the world is simply divided into 6 regions, 3 in Longitude and 2 in Latitude... and then, for each LOD level, the areas are halved. I'd appreciate if someone can shed some light on this...

Share this post


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

The Terrain SDK has a table that shows you the dimesions of each LOD cell in degrees. Just multiply this by an integer to get position lat/lon.Christian

Share this post


Link to post
Share on other sites

The table in the SDK is not accurate for the higher LOD levels. The values are rounded of for them. You can see this if you for example take the size of a LOD10 and divide it by 2 to get the LOD11, LOD12, etc.So I would suggest to calculate your own table with more accurate values. But then you can indeed get the borders as Christian suggested.

Share this post


Link to post
Share on other sites

I too have been wanting to create some photo real 'tiles' of terrain scenery, but find the SDK to be a bit sophisticated in its verbage of 'how to do one'.If only there was a step by step guide for doing it for slow people like me, lol.Bill

Share this post


Link to post
Share on other sites

Hello Bill,Please see this post:http://forums.avsim.net/dcboard.php?az=sho..._id=31890&page=Below the name of the person who started that thread you will find a link to a web site containing simple instructions for creating photo-real ground textures.He also offers, for free!, an easy-to-use tool that has succesfully been used by most of us for making this kind of scenery.In addition, he has a forum right here on Avsim where he answers questions concerning the process - when he is not off on an intercontinental adventure, that is.Good luck.Luis

Share this post


Link to post
Share on other sites

Thank you, Jon. So, it was under my nose all the time! The story of my life.Best regards.Luis

Share this post


Link to post
Share on other sites

Hi there,aside from being probably the best resource for information about all things LOD (for landscape and mesh design), Steve Greenwood's website also contains an EXCEL spreadsheet LOD boundary calculator:http://www.fs-traveler.com/resources-d.shtmlCheers, Holger

Share this post


Link to post
Share on other sites

Hi Misho.You could download "tcalc_v2.zip" from the AVSIM library. I've included the delphi source code, and from that you should be able to get your formula for LOD's.The format for LOD's is derived from quads... QMID. QMID 0 is actually larger than the earth!It's been a while, so my notes are probably trashed, but the delphi code is OK.Dick

Share this post


Link to post
Share on other sites

Hello Luis,Just wondering, that link you have is to this very thread and I think you had meant another one involving easy placement of photo terrain scenery.Hello Dick,Just a curious question. I have been dreaming of doing a terrain scenery of Mars on FS2004. Mars is a smaller diameter then Earth. Could you possibly reflect on any problems that would occurr on creating the mesh and scenery textures? For instance, if QMID-0 is larger then Earth, what would you recommend?Forgive me for changing the subject, but its rare to find out such a subject of this area of scenery design.Bill

Share this post


Link to post
Share on other sites

Hi Bill.QMID and the LOD system are measurements of degrees. Mars' latitudes and longitudes are the same as earth's...as would be any round object. What would change is the elevation, and Mars' elevational data would have to be changed to an earth system ( WGS84? ).All the data would be negative elevation in earth terms... and we do have a limit for that ( -32767 meters? ) in FS9.So if the diameter of Mars is less than the diameter of earth by 65536 meters, then sculpting Mars with FS9 wouldn't be possible. And that is true. Mars is only about 6800000 meters across, and earth is about 12756000 meters.So I don't think Mars is available for FS9.Christian would probably be better suited to confirm this.Dick

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