AccuRender nXt

advanced rendering for AutoCAD

I am having trouble with my interior rendering.  I usually do exterior stuff, but this is my second rendering using nXt.  I biggest issues are the blue lighting that I can't seem to get past, the scene isn't supposed to be that blue.  Also I have a bunch of strange white lights that are showing up and I don't know why.  Thirdly there are continuous lights that "halo" both floors that have downlighting, but they don't show up correctly.  I deleted them in this image, but I would really like to get them back.  I don't want them to overpower the image, just wash the walls a few feet.

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It's actually a pretty good image-- I left it in the gallery as well.


If you're willing,  upload the model to me and I'll take a look at it.  Otherwise, I can guess at some of the problems but I don't know for sure.  Include any necessary comments or instructions when uploading.




Wow, Awesome.  Thank you for getting back to me so fast.  I have uploaded the image and required files.  As far as the instructions go, the only thing I can say is that, on this image (there are two) the sun should be coming through the front doors...(that part is the biggest concern of my clients).  :)

I didn't have your HDRI, so I just used the standard lighting for this one (Daylight Interior preset.) Lighting the model this way, the color of the skylight and the color of the walls both contributed to the "blue" cast.  When I made both of these more neutral, using the Path Tracer for a few minutes I got the following:

Is this more what you're after?


The lights have some problems.  

First of all, the way you modeled them isn't working.  I would place a 3d face in the widest part of the luminaire and tag it as an area (diffuse?) light.  Make sure you aim the light so it points up. Second, you'll need to put accurate values in for the intensity of the lights-- 100 foot long luminaires cast much more light than 100 watt incandescent bulbs.  Speaking of which, if you're not going to use the path tracer I would definitely break those up into smaller pieces-- you'll still need to let this run quite a bit to get convergence.

Third, the daylighting can easily overwhelm this sort of lighting.  (It depends quite a bit on your HDRI.)  This phenomenon is accurate, BTW-- but if you still need to visualize your lighting you should probably put the daylighting and interior lights on different channels.  Just go to Advanced Lighting and change the # of channels to 2.  That should take care of it automatically.

I should mention that if your HDRI has some blue-- you will get some blue in the light unless you turn the saturation to 0.0.

I adjusted my rendering to the interior daylight and it turned out a lot better than before, I am still working out the lighting situation but the rendering itself is looking a lot better.  It is a little brighter than I want, but I can play with that.  I attached the progress picture.  I also attached the other view and I am still getting some odd lighting affects and I don't know where they are coming from.  It looks like I have spotlights shinning up from the base on the left and on the actual light fixture around the perimeter.  my interior lights are turned off, where are these things coming from.


All in all the quality and "sun" lighting are exactly what I need to see.  I am just having a couple of the same issues.


Thank you all for all the help thus far.


Check the INSUNITS system variable-- some how it got set to 0 in your model.  It should be set to 1 (inches).  This should take care of these indirect lighting artifacts. Sorry I missed this the first time, but the ACA UNITS command reported the units correctly.  The orginal AutoCAD DDUNITS command does show the problem. I'm not sure how a drawing gets into this state, but it is troubling.  Jan was correct about the units problem.


Try the Path Tracer for this when you get a chance.  It's the sort of interior that should converge pretty quickly and the quality may be a bit higher.


Oops, deleted my first comment by mistake. Anyway, this scene cries for path tracer. More accurate for this kind of renderings (see the short example by Roy). Correct me if i'm wrong but i think the lighting problem will be solved automatically this way, no matter how the units are set. There are other issues important of course to correct  the units. Also, turning down the sun intensity (and,or) overall brightness will correct the overexposure
Well unfortunately I couldn't get the lights to work out before I had to send it out, but here is the "final" product (The lights on the one was via Photoshop and it was done in two minutes).  I had to render them both at the same time and it rendered for 10+ hours and the one is still really grainy (Both ran with Path Tracer).  Apart from the render farm (Which I haven't set up yet) is there a better way to render large images with good quality?  Eventually they are going to ask for large format so they can put in their lobby to show what's coming, about 24X36.  I don't want to tell them that they can have it in a week.

Render at the lowest res. possible.  Experiment with upsampling using PhotoShop to see what you can get away with.  Other than that, you'll need a faster machine.  


You'll still get decent results with the other engine, and it might be faster-- particularly if you're not trying to simulate the lighting troughs.  Make sure you get the INSUNITS correct, though.

Looks great! Also, there's a difference between 10 hours and a week. Doubling the time will make a big difference.

In my opinion RPC objects need to be done very well or omitted. Because when they are done poorly they impact the overall rendering.

People seem to be lighted correctly but do not cast correct shadows.

Yeah, I agree...with my first few renderings they cast square shadows.  Is that a setting that needs to be set or is it my RCP?




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