Request for an EXR and some questions about Terragen3

[Sinnlos]

Hi there
I'm new to this forum... but i know terragen quite a while.
I have been using Terragen long time ago when it was version 1 or even lower.
I used it to make some skyboxes for my game-projects... but then i somehow lost track on terragen until now.

I got interested on Terragen3 because of the possibility to render out EXRs from a spherical-cam.
I would like to make me some custom HDRI's which i could use for rendering in 3dsMax.

So i'm planing to purchase Terragen3. But I would like to know some things before:

1. Is it possible to create an animated daylight-system that uses real world parameters?
For example: i load a DEM-Terrain and now i want the sun to behave as it would do in that location for a certain day.
So i would have to define longitude/latitude and the date/time.

2. When animating clouds, are there any presets i can use for a realistic deformation over time?

3. Is it possible to render an EXR-animation from a spherical cam?

4. And last but not least, could somebody share an EXR rendered in a spherical cam with me?
The render doesn't have to be fancy,  i just want to check how it behaves in 3ds Max.

Cheers

Sinnlos

[Oshyan]

There is no built-in time-of-day system at the moment. But I think you could fairly easily create a good enough approximation, or do the actual calculations to get it exact if necessary.

There are no built-in cloud animation presets, but animating clouds is relatively straightforward, at least at a basic level. You can try the 4D Noise option in the Power Fractal, and/or use a Translate Input Shader in-between your cloud density shader and the cloud shading node, with X/Z translation for lateral cloud motion, and Y translation for cloud "evolution". You can get some surprisingly realistic motion. Here's an animation done partly using 4D noise I believe: http://www.youtube.com/watch?v=qyDDuSUvXlQ&feature=youtu.be

Yes, you can render an animation to EXR using a spherical camera. Here's an example image:
http://www.oshyan.com/tmp/st-helens_spherical8.exr

- Oshyan

[Sinnlos]

Wow, thanks a lot for your help Oshyan!

Thanks for the Link and the EXR aswell. This really helped me for my decision to buy Terragen3.

Cheers

Sinnlos

[Oshyan]

No problem. Let us know if you have any other questions.

- Oshyan

[Sinnlos]

Hi all

So i bought Terragen 3 and im really enjoying fiddling with all the parameters and rendering some nice landscapes.

There are two thing bothering me though:

1. I also get these glitches when rendering out spherical cams just like BigBen mentions in this thread:
http://www.planetside.co.uk/forums/index.php/topic,17327.msg168204.html#msg168204

when will we receive this fix?

2.when i take the EXR into Photoshop and check the brightness of the sun and sky... the sun is bright like it should be, but the sky is not (see attachement)
[attachimg=1]   [attachimg=2]

is there something im doing wrong?... is the alpha cutting out the brightness information? thanks for any hint!

cheers

Sinlos

[Matt]

It appears to be that the exposure is low, but I don't see anything else that looks particularly wrong. What did it look like in Terragen's Render View? Was it much brighter? When you first load the EXR into Photoshop, are you able to choose the exposure level?

The brightness of the render might be affected by many things, but here are two things to check for:

1) "Light exposure" on Terragen's camera. The default is 1 (corresponding to 0 ev). It gets changed if you adjust the exposure slider in the 3D Preview.

2) The strength of the sunlight. The value in the default project is 5 (it also has a slight blue cast as a sort of white balance adjustment).

Both of those things affect the EXR, not just the display in Terragen.

Matt

[Sinnlos]

thanks matt, i will check that...

i think ill just have to test more and get myself really into terragen...

cheers

sinnlos

[gregtee]

Your sunspot value of 10 is very low to me.  I'm not sure what rendering software you're using this latlong for, but for the Liberty Life spot posted here I had a sunspot value as high as 50,000 at the sun's zenith to get the correct exposure for rendering that scene in vray.  This was based on values derived from a real, carefully calibrated HDR shot outdoors designed to render an 18% gray ball at 18% when sampled at the lightest part of the ball.   We spent a lot of time adjusting the sunspot in the HDR until we got the correct exposure.  Once we determined what that was, it was easy to duplicate those values for the Terragen sun for the commercial.  The result looked quite natural and didn't need any further adjustments in compositing software with regards to exposure. 

-Greg

[Sinnlos]

Hi Greg

Thanks for your answer. This is very interesting.
I have to admit, i'm a newbie when it comes to HDRI. I just compared the HDRI i rendered from Terragen with the HDRI's i usually use in Max/Vray (from Peter Guthrie).

But what is with the sky, does it have any brightness? In the Spot there is a moment, when the sky is full of clouds and there is a very difuse/dull light situation... in that moment only the sky would have lighten the scene. Therefore the sky you used must have brightness aswell, i guess.

A last question, if you don't mind =)
You said the sun would have a value of 50'000 at the zenith, what strength does the sun have when it's Dusk/dawn?

Cheers

Sinnlos

PS: I'll do some test and post it in this thread!

[gregtee]

At dusk/dawn the red channel has the highest values and they can vary greatly as the sun rolls off the edge of the horizon, and also depending on cloud cover, but lets assume you have no clouds in your sky blocking the sun.  As I recall my sun spot in this instance had a value of around 1600 in the red channel, the other channels having their other correspondingly lower values.  This 1600 value again, would vary greatly as the sun rose or fell, but that was an "average" value for the small time sliver from the moment the sun broke over the horizon until it gained enough altitude the time of day to no longer be considered dawn. 

Also, the animated latlong I made had no clouds in it.  At first I made one with clouds but i decided that having cloud cover in the latlong was the wrong approach for a CG time lapse light rig.  It was better to just let the sun be the sun and use other methods to indicate overcastness in the final render. 

[Sinnlos]

Hi Greg

I really appreciate your help, thanks a lot.

It's a pitty, i can not test these things at the moment because i have a lot of other work to do... but as soon as i get some spare time i will post my results here. I guess it could be useful for other people here in the forum.

And also i want to give something back to the community... at the moment im only taking 

Cheers

Sinnlos