Raytrace and Radiosity Comparison

[Allan Chesney]

If you are wondering what the differences are in these render types the attached images may help.

The image on the left is Raytrace only (View/Render 3D Real View and click Render)

The image on the left was done from View/Render 3D Real View but clicking the Advanced tab first and click Step 1 (Radiosity) then Step 2 (unless you have that set to automatic).

How do they compare?
At first glance Raytrace probably looks better, is brighter, has excellent reflections and works very quick (about 30 sec for 640x480 image).  However it really is too bright for a 100W light, the wall on the left being far too bright (especially at the top of the wall) and there is too much light on the ceiling for a light that is pointing down (even though I have the shade set as semi transparent).  The car has also losts its colour almost completely.

Radiosity (+ Raytrace) takes longer (several minutes at top quality 5), is darker (as you would expect from a 100W light in a big room) but the shadows are more natural. There is distinct shade under the car, while on the Raytrace only image you can even see the inside rim of the wheel for example.  Given that the light is immediatley above the car and it is the only light in the room, it should be dark underneath it and in the Radiosity version it is!  It would likewise be bright in the seat area - and it is!  The Raytrace only version falls down on realism in these areas.

True the Radioisity vehicle itself looks worse (back yard panelbeater!!!) but that is the fault of the 3DS model not the render. The Raytrace vehicle looks better but the reflections around the front corner are just the flat spots on the model not reflections from elsewhere.

So I suppose it depends what you are doing, how accurate you want the results to be and how long you want the render to take.  Rayrace shadows are hard - note the shadows of the car on the surrounding tiles and of the lamp shade on the ceiling.  Radioisty shadows are much softer and more natural - but they take longer.  Worth waiting for if you want accuracy (unless you have been to a rotten panelbeater!).

Allan

[Doug.S]

Thanks for the info.

With h/w acceleration settings showing render "issues", wondering if you would be willing to email me or post your .bld source file for these renders....and any special rendering instructions (image size for example) or anything else I'd need to set to exactly duplicate your setup.

Sole purpose is for me to open your file as-is and render exactly the same file as you on my PC and see if the renders come out differently.  I know now I must render with h/w acceleration "off" or renders are washed out.  But for raytrace renders I don't seem to get the same kind of shadows on the ceiling...at least from my experiments with this trial program installed.

Thanks,

Doug.S

[Shonner]

Lighting is 50% of your render's quality.  An object's materials also determine how well it renders.

[Allan Chesney]

Doug,

I tried to email the file to you but the email from your profile bounced for some reason.

It is not hardware acelleration that causes the washed out lighting. With HA on the Rasdiosity option causes it to crash. From my latest tests (See Tips and Tricks forum) the lighting issue seems to have something to do with Radiosity not resetting unless the project or even the program is closed and re-opened.  Having Daylight enabled also seems to brighten multiple lights dramatically. Not sure if that is the case with single ones yet.

Will send the file if you can clarify the email address.

Allan