topic Re: Lighting problem during rendering in AutoCAD Forum

Lighting problem during rendering

ge_langellotti — Wed, 17 Sep 2025 17:42:37 GMT

Hi, I'm having trouble managing lights when rendering in AutoCAD. Can someone explain what the problem might be? I've attached some screenshots of the problem.

Re: Lighting problem during rendering

Alfred.NESWADBA — Thu, 18 Sep 2025 09:07:36 GMT

Hi,

can you describe the problem you have? I see screenshots with markers, but I don't recognize the question you have regarding these markers (maybe it's just me, but it would help to have a description anyway).

Also uploading the dwg-file is needed, we can't see settings like render settings, units, light-properties, shadow settings in just screenshots.

- alfred -

Re: Lighting problem during rendering

ge_langellotti — Thu, 18 Sep 2025 09:39:10 GMT

Hi, thanks for replying. The problem is that I position the light sources in the pre-established points of the LED spotlights but when I start the automatic rendering the lights point in a completely different direction. As you can see from the images, I placed a central light but in the rendering it appears at the bottom.

Re: Lighting problem during rendering

Alfred.NESWADBA — Thu, 18 Sep 2025 10:01:20 GMT

Hi,

>> As you can see from the images, I placed a central light

And the global render settings, and the settings of material and their reflectivity (which means light rays land on surfaces after being mirrored multiple times, ...) and the render settings and ...

It's just guessing, this guessing could go for days now, uploading the drawing makes a job of guessing over days maybe (hopefully) a real solution in hours.

- alfred -

Re: Lighting problem during rendering

ge_langellotti — Thu, 18 Sep 2025 10:12:36 GMT

thank

Re: Lighting problem during rendering

Alfred.NESWADBA — Thu, 18 Sep 2025 13:34:42 GMT

Hi,

first I see your units are set to Millimeter, however, the distance between light and floor shows 2.7.

This means the floor gets as light as it is 2.7mm away from the light source!

And as the light intensity is such high it gets reflected to the ceiling and most probably has the same intensity as the ray passed 5.4mm (Millimeter!), I guess this describes why all is such light.

I started render with camera "Copis (2)..." and got the result (with your units setting, only changed "render accuracy" to draft)

Then I changed units to Meter, rendered, and this is the result now:

So your issues are mixed between:

wrong units ==> change it to Meter using the command _UNITS or -DWGUNITS
wrong light intensity, set to 10 which is too low, change it to a value like 1500 (which is the default for spots in AutoCAD)
intensity factor was set to 5, well it's a combination of 2 values, factor and intensity, at least I would not play with both values
render exposure

I used now

units Meter
light intensity 2000 (and added a spot for each of your lamps)
intensity factor = 1
render accuracy = draft (which I would always prefer instead of high)
render exposure to 8.8 (was 10 while 8.8 is default)

...and got this, hopefully a good state for you to continue:

- alfred -

Re: Lighting problem during rendering

Alfred.NESWADBA — Thu, 18 Sep 2025 11:53:36 GMT

One more result with following changes:

spotlights angles changed to 110/150 (hotspot/falloff)
exposure from 8.8 to 7.1

And result is:

- alfred -

Re: Lighting problem during rendering

ge_langellotti — Thu, 18 Sep 2025 13:42:57 GMT

Thank you so much for your help.