What are good "Ray trace everything" Settings

Started by John-117, March 07, 2010, 10:24:11 pm

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Hello, I am thinking of entering a modeling contest.  I would like to use Terragen 2 however, one of the requirements for the contest is the use of ray tracing only.  I realize that because somethings in Terragen 2 are not optimized for ray tracing only I will take a small quality hit in some areas.  To this end I would like to know 2 things:

1) What ray tracing only settings will keep this quality reduction to a minimum.

2) What are good ray tracing only settings for a typical scene (eg. sunny day, high clouds, medium 3D volumetric clouds, small rolling hills, a lake, a few hundred objects and maybe a moon or two.)

Any suggestions would be appreciated, thanks. 


@Kevin F  Thanks for the link, however I have already read the guide several times and implemented all the recommendations (except actually not using "Ray trace everything" on landscape scenes).  The results were still unacceptable:

Ray Traced only (Quality = 1, Anti-aliasing=8)

Quick Render (default settings)

As I am new to Terragen/Terragen 2, what I would like is for someone who has experimented with the ray tracing only option to tell me one of two things:

1) Is this is as good as I am likely to get with "Ray trace everything" only and therefore I either should come up some creative camera + object scenes to hide close in terrain or not use Terragen 2 for this project.

2) If Terragen 2 is able to preform better than this with "Ray trace everything" only what settings should I modify to achieve improved results.

Thanks for your help.


For objects, choose to only Ray Trace your objects. 

There is a marked difference in the two renders, but you need to change your cloud settings and maybe atmosphere settings, too.  That's why these both look like crap.
So this is Disney World.  Can we live here?


@calico  Thanks for you thoughts, both the images were low resolution test renders just to see the difference between ray trace only and regular renders so they are not meant to look perfect.  I am not to worried about the clouds as I did not tweak them and they are one of the things Terragen 2's ray trace engine does better then it's rasterization engine.  My main concern is the terrain detail.  The top ray traced image lacks most of the detail of bottom "normally" render image (granted the ground detail there is probably more than is realistic).


March 08, 2010, 12:47:31 pm #5 Last Edit: March 08, 2010, 12:49:47 pm by 6y4cd93v
Some higher resolution examples:

Ray traced render (Quality = 1, Anti-aliasing=8)

Normal render (Quality = 0.8, Anti-aliasing=8)


The ray tracer won't help your terrain in the slightest. Using RTE is best for scenes that; You cannot see the ground or, the ground is completely covered with objects or, you are rendering very distant terrain that you don't need to see great detail on.

In general, Planetside's advice in the RT advice thread is good. Use RTO for a scene like this, and, you really don't even need that checked, since you haven't any objects in it at all.

The rasterizer is your best bet here. Higher cloud quality samples will remove the grain from the clouds, higher atmosphere samples will remove the grain from the atmosphere.

The main problem I see here is that the shadowed areas of the clouds are a bit noisy on the rasterizer render. To remove this, atmosphere samples are required, not more cloud samples.


March 08, 2010, 02:24:16 pm #7 Last Edit: March 08, 2010, 02:26:06 pm by 6y4cd93v
@ dandelO  "The ray tracer won't help your terrain in the slightest."  Thank you very much, that is exactly what I wanted to know.  If therefore I use Terragen 2 for this ray tracing contest as I was thinking, I will, as you said have to hide close up terrain with objects.  

"Higher cloud quality samples will remove the grain from the clouds, higher atmosphere samples will remove the grain from the atmosphere ... "  While I appreciate all the tips you and other users are giving about clouds/atmosphere and I am sure you are right, all the posted images are simply for the purpose determining how Terragen 2 handles the "ray trace everything" parameter as apposed to the rasterization/ray tracing composite render.  This in turn is to see whether Terragen 2 is suitable at all for the ray tracing contest I was thinking of entering.  So yes, if these images were final drafts I would find your comments on clouds/atmosphere very help.  They are however just viability tests for using only Terragen 2's ray tracer which should have no problem rendering clouds/atmosphere in the final yet to be created image.


One thing that is tricky to grasp about TG2 is that Atmospheric Samples will make the entire scene look better when handled with finesse.  It's the difference between a sweet render by Seth (for example) and one I might have done before I learned about using the Environment Lighting as an asset.
So this is Disney World.  Can we live here?


Isn't Global Illumination a form of Raytracing anyway?

Does your competition say you can't use GI? It seems like you maybe taking the rules and Terragen's termanology too literally!?


@calico  Thanks, I'll make sure to pay particular attention to the atmospheric samples on the final image.


March 09, 2010, 04:09:59 pm #11 Last Edit: March 10, 2010, 04:10:16 pm by 6y4cd93v
@Hetzen  "Isn't Global Illumination a form of Raytracing anyway?"  Yes and no, it really depends on the algorithm used and I don't know how Terragen 2 handles it.

"Does your competition say you can't use GI?"  No it does not say anything about it, however submissions have to be 100% ray traced and no post-processing beyond adjusting contrast, cropping and resizing.

"It seems like you maybe taking the rules and Terragen's termanology too literally!?"  Your probable right but I would hate to have the nicest image submitted only to be disqualified.

The key thing is the image has to be completely ray traced with no rasterizer rendering at all.  I would be open to anyway of doing this Terragen 2 has to offer, however as I am new to it I am not that familiar with my options.



To achieve equivalent terrain quality when Raytrace All is activated, you'll need to set the detail setting to 4 times what you would use with the normal renderer. So if you would render at 0.5 without Raytrace All, you'd need to use Detail 2 for equivalent terrain detail. For 0.75 (a pretty high quality really), you'd use detail 3. Of course this will result in much longer render times. If you're using GI this can be particularly problematic since GI Detail is *Relative* Detail. So if you're using e.g. Relative Detail of 2 or 3, set that back down to 1. Ideally you would avoid use of GI since it's hard to get it low enough to compensate for the huge detail increase (since fractional values are not possible). Also if you don't have vegetation or other objects, you can use really low AA values with normal atmosphere and cloud sample values (e.g. quality 1 for a cloud layer), and still achieve very low noise results with decent speed. The terrain rendering is really going to be your biggest issue, but if you're determined to enter the contest, this is the way you'll need to do it.

It really does take a while to get used to how differently the settings will behave when everything is raytraced. For some scenes it can be worth it, but for your purposes this is obviously not for efficiency or quality.

- Oshyan


@Oshyan  Thanks for the info it was very helpful.  While I tinkered with the ray trace everything settings quite a bit I was only able to achieve marginal success at the cost of a lot of time.


In case anyone else whats to use "Ray Trace Everything" for terrain scenes here is a summary of Oshyan's suggestions with my input added.

1) Increase the detail by a factor of 4.

Example: if the detail is 0.8 then change it to 3.2 (0.8*4=3.2).

This is VERY important.  Without doing this your terrain will look triangulated (read very ugly).

2) Set GI Relative Detail down to 1.

This cuts down render time while not reducing that quality much at all.

3) Use really low AA values.

This cuts down on render time. This setting will need some experimentation based on your scene.  I found AA values of 1 or 2 to low (while the terrain detail was great the coloring on the terrain looked "chunky").  Three seemed to be a good compromise between quality and render time.

Thanks again Oshyan