General Question Elevation grid calculation and missing tiles

[Sword7]

I am writing my OpenGL program to display planet from Orbiter data files. I have some problems with loading image and elevation tiles. I checked database files and noticed some tiles are missing at that deeper (higher) LOD level. It displayed some blank tiles on my screen.

I tried to display all four valid tiles at LOD level but images are too blurry (lower LOD level). I changed codes to display any valid tiles (less than 4 valid tiles) and it go much deeper LOD levels but displayed some blank (black) tiles.

However, I noticed OVP clients that were able display all tiles (not missing tiles) and looked into OVP client source codes but can't find any code to display valid lower LOD level tile to cover missing higher LOD level tiles.

How to display missing image tile at higher LOD level by using partial lower LOD valid tile?

For elevation grid tiles, I found out that elevation grid calculation is in Orbiter core (closed source). Does anyone know any elevation grid algorithms to display higher resolution tile by using lower LOD level tile?

Thanks,
Sword7

 

[Face]

Does anyone know any elevation grid algorithms to display higher resolution tile by using lower LOD level tile?

Bicubic spline interpolation?

 

[Sword7]

Bicubic spline interpolation?

Thanks. Got it now. I googled about elevation grid interpolation and found some sources. Orbiter SDK manuals did not say that in ElevationGrid function call.

One remaining question is still unanswered... How to display partial lower LOD texture tile (due to non-existent tiles at current LOD level) at higher LOD level since last valid tile was available at lower LOD level? Orbiter SDK (Planet Texture files) manuals did not mention that non-existent tiles at higher LOD level. If not, I will ask that in GameDev forum later.

Update: I resolved the problem when updated new loading routines to loading valid lower LOD tiles when non-existent tiles were detected.