AccuRender nXt

advanced rendering for AutoCAD

This one introduces two new engines.  Both of these are very experimental at the moment. I may not retain either of them if they don't prove useful.  Although they appear very stable, there may be some hidden bugs.  Be careful using these for production until we have some confidence in their stability and characteristics.  The engines are only accessible via the nXtEngine AutoLisp command use (nXtEngine 2) -OR- (nXtEngine 3).


Both engines include more light pathways than the current product does and can therefore potentially provide more accurate solutions.  Two "tricks" which are used in the first two engines, transparent shadow rays and daylight portals, are not used in these new engines.  This gets rid of two big sources of inaccuracy.  Caustics pathways are automatically included.

Engine 2 can be much less noisy than the Path Tracer for most interiors.  It's convergence, on the other hand,  is not as graceful and will include some discrete artifacts.  It's usually a lot faster than the Path Tracer for interiors.

Engine 3 is a little more accurate than Engine 2, particularly when window coverings are involved.  It converges more gracefully, but slower for some interiors.  It is considerably faster on some exteriors.

Some things to keep in mind with these engines:

  • Light leaks in the corners are possible when doing interiors.  Make sure walls, floors and ceilings are modeled as slabs with thickness.
  • Both engines start slowly and accelerate.  Pixels/sec should increase as they proceed.
  • Using accurate IORs is very important.  IORs of 1.00 should not be used for glass.
  • Designating glass as Thick/Thin is more important with these engines.
  • Translucency is not implemented.  Allow Surface Roughness is.
  • These engines use more memory than the previous two.  64 bit is recommended.  Start your testing and low resolutions.

Let me know what you think-- I'm looking for feedback here.


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hmmm... the eye of the master...

I forgot to mention the light leak which i noticed too.  the ceiling is a solid but doesn't overlap the walls. I assume that must be the reason. It only appears at the sun channel.

You're right, Roy, the light is more subtle and realist with E2 but I agree with Jan that the light through the curtain is much better with the E1. Could it be corrected in the E2? The difference of saturation between both images (floor), is it due to a regulation of the tone mapping of the E2 ?

You might like it better-- but the PT is quite likely to be wrong in this case.  Items close to daylight portals are all suspect. Absent any light leaks, e3 is the most likely to get this right.  The example below, the missing glossiness, is much more concerning. 

An important difference...

The 3 images: the same render time? I believe it' better to compare the render time, and not the number of pass. Im I wrong?

Totalmente de acuerdo con Marc, lo importante es medir el tiempo de proceso. El numero de pases no es un parametro.

Je suis d'accord

rendering time is almost the same indeed. I'm afraid when i keep using all the bells and whistles in this programm (which are fantastic by the way) i'll have to think about bying another machine. Each rendering took overnight and still doesn't satisfy me.

 

Any chance you can upload this model?

Here we go! Sorry for delaying, but I've been terribly busy with job stuf (which not always are enjoyable as experimenting with nXt!!). So, this is the most complex model I have, rendered it with e1, e2 and e3. At first glance, I still prefer e1, if it had more reasonable time of rendering and much less "grain effect". What I've noticed is that e1 starts to process all lights first (is it correct Roy?), while e2 and e3 are taking into account lights later (look at blue LED light on the ceiling). On e2, I don't like the treatment of the shadow on the floor of the wall with the black painting, and the illumination of the white brick wall above the sax (light is a fluorescent tube). On the other hand, brick bump is definitely really nicer here than with other engines. When e2 started, there was the same artifact that is visible on e3 image: the white line at the end of the window frame on top, but it disapeared while rendering, while in e3 is still present despite of the 1677 passes! Colour saturation is great in e2, a little too much in my opinion (i.e. see cristal table), but I like it treats the exterior light, which is too much overexposed in e3. Please coment what you think!

I know I've got this model-- it's so big it's difficult to work with.  What's lighting the skylight near the piano? (Still the most significant source of error in e2 that I need to figure out).  

The lack of noise in e2 is encouraging-- and I think I can do it much faster.  You might like e1 better, but it's going to take forever to converge.  Some glossiness is missing from the chalkboard in both of the new engines.  The benefit from caustics in this scene is difficult to see-- although the light with the metal dome is being handled much better in the new engines.

De acuerdo con Roy. Los nuevos motores son mas rapidos ademas de tener una mejor representacion de cauticos, y un poco mas de profundidad y luminosidad

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