Why AUTOCAD doesn't render light?

[Anonymous]

Hi my Autocad 2019 does rendering correctly offline. But I want to render 360 panorama view and I don't know why there is no light inside the room. I added lights inside the room.render rightrender wrong

[Alfred.NESWADBA]

Hi,

when I render your file (locally) I get that result:

Did you really upload the dwg that you used for your local rendered image?

- alfred -

[dbroad · Accepted solution]

Great question. The truth is that AutoCAD used to do a lot better in rendering and lighting.  When they dropped support for Mental Ray and even before that, they were already dropping features that supported high quality rendering in AutoCAD.

Lights used to have a lot more support in the properties palette.  They used to be able to be shaped and would actually render that shape visible in the render.  It used to be possible to create scenes with preset light on/off states.  The scene command is no longer.  While you can tweak lights to add shapes and can set their visibility in rendering, those settings must be done when the lights are added and the features are hidden in nested subcommands. The properties palette will never report those settings because the rendered shadow details section for lights was entirely removed from the properties palette. This could be to hide the fact that those settings don't make any difference in the renderings using the physical engine.

AutoCAD relies on web lights more for lighting distribution but that doesn't really match the level of precision that AutoCAD once had.  You could shape a light as a rectangle and as a tube as well as a sphere and the light would actually cast light as if was being illuminated by that shape.  The loss of these capabilities in lighting would be easier to accept if AutoDesk had added a property for materials that controlled whether a material casts shadows. Those features, however are now only in 3DS Max.  So you have to buy that program to get a decent render with lights. If you create a self-illuminating material and apply it to a solid with a shape, the distribution of light doesn't match the shape of the solid and the solid casts its own shadow on each surface receiving its light. That doesn't even make sense.  If you set the transparency of a self illuminating material between 85% and 95%, however, you can still see some of the self-illuminating surface without it casting a definable shadow.

The new focus for AutoCAD is rendering as a pay-per-render cloud service.  So instead of buying a decent professional level graphics card, you pay for each render in cloud credits. Thank goodness, I never discarded my 2012 version.  So much for the subscription service adding annual features.

[Anonymous]

Thank you all for answers. I began to use 3ds max because I couldn't have solved the problem with lights in Cloud rendering. The only solution for me was to create room without light. I close this topic.

[Anonymous]

I probably changed the strength of lights. But in Cloud Rendering I receive black background.

[dbroad · Accepted solution]

The images attached are a hall similar to yours about 6'-6" wide with accoustical tile ceiling and a radial tile floor pattern.  I added a single light above the ceiling so that default lighting would turn off. Then I added a single cylinder, 20' long with a generic material about 60 percent transparent with frosted bulb self-illumination.  I then added a reflector surface with a mirror material.  The first picture is the medium image rendered locally.  Anything higher than medium render results in poorly rendered, grainy pixelations. I believe that this is a flaw in the physical rendering engine as it is applied on a local machine.  Coffee break quality and lunch quality have more pixels but the bright spots remain.  The second image is a low-cloud credit render (the default).  It is much better but a bit splotchy on the GWB.

Local medium renderLowest quality cloud render