Board index FlightGear Development New features

Terrain elevation in EarthView?

Discussion and requests for new features. Please note that FlightGear developers are volunteers and may or may not be able to consider these requests.

Terrain elevation in EarthView?

Postby eatdirt » Thu Sep 20, 2018 11:50 am

Hello,
I am a completely new user to FG, playing with the SpaceShuttle, one of my kid's dream. I am especially enjoying the view and all the work made for the rendering!

Dunno if this is the right place to post, but I may suggest, if doable, that a step further could be to add a terrain elevation within EarthView?

The only experience I have with this comes from my screen background rendered by xplanet: http://xplanet.sourceforge.net, see below.
Shadows created by mountains are stunning, especially at sunset and sunrise, all volcanic islands become very visible!

Image

Of course xplanet is doing this at 1 frame every 10mn, I have no idea if this is even thinkable for EarthView!

Thanks to all for all the work done!
Cheers,
Chris
eatdirt
 
Posts: 234
Joined: Wed Aug 15, 2018 2:06 pm

Re: Terrain elevation in EarthView?

Postby Thorsten » Thu Sep 20, 2018 12:07 pm

Not sure what you hope to see, but:

* we have the correct shading of terrain in low light:

Image

* we even have the correct relief on clouds in low light and parallax displacement during the day:

Image

* we render parallax displacement of mountain regions using a heightmap and reduce the atmosphere scattering in high regions

Without heightmap:

Image

With heightmap:

Image

So what do you think we're missing?

The fact of the matter is that mountains aren't that high when seen from orbit though, so all of this is fairly subtle (your desktop is *cough* exaggerating a lot...)
Thorsten
 
Posts: 10434
Joined: Mon Nov 02, 2009 8:33 am

Re: Terrain elevation in EarthView?

Postby eatdirt » Thu Sep 20, 2018 12:15 pm

Thanks Thorsten!

Apparently nothing then. Maybe my problem is that I am used to the xplanet rendering, in which the mountains' shadows are very visible, even from quite far (see picture).

About xplanet, I did not dig into the code, but the main developer seems to know his business as well:

http://crism.jhuapl.edu/mission/profiles/Nair.php

I doubt he has exaggerated the shadows, but clearly all atmospheric effects are absent.

It may be my fault though, I have followed this page http://wiki.flightgear.org/Earthview to use 16K textures for earth, with this script:
https://github.com/chris-blues/Nasa2FGearthview

so maybe I have broken somehow the height-map rendering by doing so?
Last edited by eatdirt on Thu Sep 20, 2018 12:39 pm, edited 1 time in total.
eatdirt
 
Posts: 234
Joined: Wed Aug 15, 2018 2:06 pm

Re: Terrain elevation in EarthView?

Postby Thorsten » Thu Sep 20, 2018 12:31 pm

I dunno how the script does the normal maps (the heightmap is in the alpha channel of the normal map) - I know Chris did a 16k set of dds textures with all bells and whistles (which I have installed), but I'm not sure whether you get this automagically.
Thorsten
 
Posts: 10434
Joined: Mon Nov 02, 2009 8:33 am


Re: Terrain elevation in EarthView?

Postby eatdirt » Thu Sep 20, 2018 3:24 pm

Thorsten, I have read this:

http://www.science-and-fiction.org/rend ... sl_11.html

Before to let it go, and without any offence, I am a fan of your work, am I correct to say that normalmaps and heigthmaps won't be able to produce the correct length of shadows in grazing lights?

Thanks!
eatdirt
 
Posts: 234
Joined: Wed Aug 15, 2018 2:06 pm

Re: Terrain elevation in EarthView?

Postby Thorsten » Thu Sep 20, 2018 3:30 pm

A heightmap actually can conceptually, a normal map not (however, for Earth this is perhaps not overly relevant, compared to the overall scale of 6700 km, a mountain of 8 km size is a 1/800 correction. Even the tallest mountains really are roughness on the sphere, nothing more).
Thorsten
 
Posts: 10434
Joined: Mon Nov 02, 2009 8:33 am

Re: Terrain elevation in EarthView?

Postby GinGin » Sat Sep 22, 2018 7:55 am

Very interesting that elevation stuff.
You got it with the hd dds tiles Thorsten? Or is there something special to do with it ?

Nice link eat dirt
FG Saturday I guess :)
GinGin
 
Posts: 558
Joined: Wed Jul 05, 2017 10:41 am
Location: Paris
Callsign: Gingin

Re: Terrain elevation in EarthView?

Postby Thorsten » Sat Sep 22, 2018 8:13 am

The elevation is baked into the alpha channel of the (HD) normal map - if you look into the Earthview thread, Chris did this on my request, and it definitely is in the normal maps I have - I'm not quite sure what's for download (I'm sitting on a GSM connection, GB-sized file downloads are something that's not done on a whim but needs to be planned well in advance here) - I guess simply contacting Chris (chris_blues) and asking for how the normal+ heightmap can be obtained is easiest.
Thorsten
 
Posts: 10434
Joined: Mon Nov 02, 2009 8:33 am

Re: Terrain elevation in EarthView?

Postby GinGin » Sat Sep 22, 2018 8:53 am

Alright thanks :)
I will do that and have a look to the earth view Wikipedia again
GinGin
 
Posts: 558
Joined: Wed Jul 05, 2017 10:41 am
Location: Paris
Callsign: Gingin


Return to New features

Who is online

Users browsing this forum: Google [Bot] and 1 guest