AccuRender nXt

advanced rendering for AutoCAD

I am setting up an interior animation and would like some help on lighting.


The issue I am having is that I would like to find a better balance with the environment light coming through the exterior glass.  The space, particularly the ceiling, feel dark to me considering the large amount of windows lighting the space.

If I increase the sky intensity then it completely washes out the mullions which are important for me to show.  I also would like to see the clouds through the glass which is shown on other views. The cloud image is a planar map to a surface outside the glass. 


 I'll upload a small sample of the animation for an example as well.


I am using the sun, background at visible sky intensity at .001, interior lights on and sky at auto.



cloud .75

sun 1

Sky intensity: .009

brightness: .30



cloud .75

sun 1

Sky intensity: .5

brightness .30



same as b except brightness at 0

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Draft segment of animation

Very nice little animation.  Have you considered a pano for this?  Seems like a good application for one....

As far as lighting goes, I can help you by checking to make sure nothing's wrong with the input to the simulation-- if you're willing to send the model.  Use the upload link if you decide to.  (I can't really help you to get the picture you want by "faking" it-- that'll be for others to try.)

If you want to check yourself-- things to watch out for include:

  • Make sure your units are correct (I think yours are, but it's the first thing I'd check.)
  • Make sure the output values for the luminaires are realistic for the project.
  • Note the # of light sources wrt the # of passes-- 8 light sources are calculated per pass.  (It may take a lot of passes to adequately resolve this interior.)


Thanks Roy:

I'm not really that intersted in taking alot of time to "fake" the image although I'm not going to be anal about making sure the lighting is correctly simulating the space either.  I didn't budget the time for it. My question for you is under a scenario where it's a cloudy day (cloudiness set to .75) then is it normal to place  the sky intensity down to the .009 range in order to see out of the window and/or not have the specular glow washout the window framing?


I'll be happy to post the model If you don't mind taking a look.  One odditiy is the wave ceiling.  It's a solid that I did a boolean subtract for the holes for the recessed cans.  When the light object was created it made a single solid for all the lights.  Not sure how nxt is looking at this fixture so my wattage values may be off for this one.


Thanks for the reply


It's hard to say-- what the tone-maping may be telling you is that there's a lot of glare coming from the windows.  If that area of your rendering is very much brighter than the rest of it-- that will happen.  That's actually decent information for the design-- the windows may need to be high ior (1.6 or so) or be tinted or laminated.

Of course, if the lighting values for the interior luminaires aren't good then it may be understating the amount of light inside.  The single solid object for a light does sound suspect.


Ultimately, if you need to get a certain picture regardless of what the simulation is telling you, then you may need to resort to things like drastically cutting the amount of daylight.  This is what I consider "fakery"-- as are devices like adding glow to your ceiling.  You're definitely fighting the product at this point, but it may be necessary.

I did boost the interior lighting a bit.  The cans are all being considered a single source (not great, but it will kind of work.)  I changed them from 500 watts to about 8800 (150000 lumens).  Doubled the brightness of the linear diffusers as well to bring them more in line w/ real-world values.


Here's what I get returning everything to defaults and using the path tracer.  It's not quite converged yet after 1.5 hours but you get the idea.  Sun and sky and background are all returned to 1.0.  Got rid of the background billboard (I'm not crazy about this approach-- prefer a spherical HDRI.) Cloudiness set to 0.2.  Put the daylighting on one channel and the artificial lights on another.  It looks pretty good to me in terms of simulated light transport.


Still think this is a great application for a panorama.  The packet tracer version was very slow-- I'm really surprised you got this to move at all.  Try using the Glossy switch where appropriate to improve performance.  Turn off all of the light sources you don't need.

I like what you have done and I appreciate the input.  Attached was my tweaked version from our conversation yesterday.  I added to omni lights to lighten the ceiling and plane.  Also bumped the glass to 1.8 ior and added a tint.  I like the floor reflections but they just are bogging me down too much so from an animation standpoint I just cant afford them. 


My system is processing about 1 frame an hour.  If I keep this pace it won't be done till Christmas.  I have to find a way to speed up the performance to meet my deadline.


I like the concept of the panorama but I am committed to delivering a self running animation to the client that highlights 4 rooms. This view of the terminal is the most difficult.  Is there a way to generate a single panorama of this terminal space. then export out to single frames a slow 360 turn around the room?  Then I could stitch together my intro's and transitions.  Any thoughts on how to accomplish this one? 




Maybe-- you'll certainly have to do a little research.

Check out this guy's stuff.  It was generated in the SketchUp (IRender) version of nXt and uses commercial panorama software by EasyPano.  I don't know if it can be fully scripted but it does spin by itself.  I can put you in touch with the user who created these.

I've heard that the Pure guys may have fully scripted players-- but you'll need to investigate.


I am getting different results.  Not sure where I'm going wrong on this one.  I have increased interior lights by double, increased wave spots from 500 to 9600.  Set glossy for floor which greatly improved my processing time, but I still cant get the exterior glass to keep from blowing out unless I drop the sun channel down to a really low range.  I feel like I'm doing something wrong here. 


Not your fault, no-- I get the same thing-- or something very similar with the Packet Tracer engine.  There is insufficient daylight reaching the center of the lobby-- not entirely unexpected given the shear number of daylight sources in this model.  There are things you can do to attempt to remedy this-- but I'm not even going to suggest anything here since it won't be appropriate for animation.  This is going to be a very, very difficult space to animate given the state of the art today.  Forcing the thing by radically altering the simulation to get closer to the picture you want may be your only option.




I'm putting together panorama options for each of the space now.  Hopefully I can sell them on this approach. I think if I can get something to play this in a 360 like your link on the earlier post, then I can use a capture card to save it to a movie file.  I have an old version of premier to do transitions and save to an avi file.


I haven't played with pano's since back in ar3/smoothmove so this should be interesting. Does anyone have suggestions on a cheap, easy player?  :)


There was a discussion here a while back-- it might have some info.


This is a direct discussion on converting panos to avi.  The entire site is quite good for general pano. info.




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Peter Milner replied to Roy Hirshkowitz's discussion AccuRender Studio
"Yes, the glass material translated as Refractive automatically."
Dec 23, 2020
Roy Hirshkowitz replied to Roy Hirshkowitz's discussion AccuRender Studio
"Yeah-- like I mentioned the caustics are accurate but could be annoying.  Things that might alter it include changing the sun angle so it's not striking the chair's metal surfaces so directly, changing the roughness of the chair…"
Dec 23, 2020
Peter Milner replied to Roy Hirshkowitz's discussion AccuRender Studio
"Here's the latest render using metallic materials. The chrome now looks a lot better. I do feel though that the reflected light on the back wall is too bright."
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Roy Hirshkowitz replied to Roy Hirshkowitz's discussion AccuRender Studio
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Peter Milner replied to Roy Hirshkowitz's discussion AccuRender Studio
"Pacing a mirror on the back wall (reflections = 1.0, noise = 0.0), you can see the difference more clearly (top image is nXt)."
Dec 18, 2020
Peter Milner replied to Roy Hirshkowitz's discussion AccuRender Studio
"You can see from these two images that there is definitely something wrong with reflective surfaces. It appears the light is being reflected, but not objects or textures. In the nXt version (top image), the carpet texture is being reflected in the…"
Dec 18, 2020
Roy Hirshkowitz replied to Roy Hirshkowitz's discussion AccuRender Studio
"It's interesting-- overall the quality of this interior is very high for that short amount of processing, and may be acceptable for certain scenes.  In this one, however, there are some reflective caustics that are taking longer to…"
Dec 17, 2020
Peter Milner replied to Roy Hirshkowitz's discussion AccuRender Studio
"ARDECAL now works. Here's the image after 10 minutes of rendering. I do have a slight concern that reflective surfaces seem rather dull. This is particularly evident on the end frame of the desk and the base of the chair."
Dec 17, 2020

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