Lighting a night time scene in POVRay.

[Hughes]

Hello, fellow AFOLs and LDrawers.

I would like to ask for some advice, please.

I wish to render some of my LDraw models in a night setting. In other words, they will be in darkness (or near darkness), but I would like light to appear to come from inside the model. Think lights coming from the window of a house and illuminating the street.

My usual method is to model in LDCAD and use its export feature to generate a .pov file, which I then render using POVRay. I have been learning how to edit the .pov file to alter the lighting, change the floor etc. I tried to place a lightsource inside the scene, but this is clearly the wrong way to do it. Can anyone offer advice on how to achieve what I am trying to do?

Apologies if this topic has already been covered elsewhere.

Many thanks,

Max

[Roland Melkert]

I tried to place a lightsource inside the scene, but this is clearly the wrong way to do it. Can anyone offer advice on how to achieve what I am

This is the correct way, it's probably just about finding the right coordinates.

For example to modify 5580 just change the default lights color to something dimmer:

Code:

color srgb <0.2,0.2,0.2>

and add a point light below it (just above //=====Cameras...)

Code:

light_source {
  <50,-208,120>, rgb <1,0.75,0> //an orange light
}

resulting in:
   

To find the new lights position you could use e.g a temporary 1x1 plate.

[Hughes]

This is the correct way, it's probably just about finding the right coordinates.

For example to modify 5580 just change the default lights color to something dimmer:

Code:

color srgb <0.2,0.2,0.2>

and add a point light below it (just above //=====Cameras...)

Code:

light_source {
  <50,-208,120>, rgb <1,0.75,0> //an orange light
}

resulting in:


To find the new lights position you could use e.g a temporary 1x1 plate.

Thank you very much indeed for your very helpful and prompt reply, Roland. I managed to render the attached image by following your advice.

    Now I need to become more expert in choice of lights, position etc.

[Hughes]

Could I please ask one more question to the forum members?

In the rendered image I would like the lamps on the platform to glow so that the light does not appear to come from nowhere.

Looking at the POVRay documentation, I have been trying to create a lightsource and use the looks_like keyword to achieve this effect, as described here: Assigning an Object to a Light Source. The object I want to assign to the lightsource is 3941.dat. As far as I understand the .pov file, this gets changed into an object entitled sf_3941_dot_dat. So I basically tried to add the following lines into the .pov file, having added a declaration at the beginning of the file stating #declare Lightbulb=sf_3941_dot_dat.

Code:

light_source {
    <820,-192,-140>
    color srgb <1,1,1>
    looks_like { Lightbulb }
  }   //illuminate the light itself. This is the left platform light.

Please excuse my lack of programming know-how. I am really just making a wild guess how to achieve the result!

Either I am on the wrong track or I am doing something wrong, as the file is parsed without errors, but nothing seems to change in the image. 

Any advice, please? Many thanks.

[Roland Melkert]

Any advice, please? Many thanks.

i.m. not sure, have you tried without the original 3941 bricks?

or maybe test at a different, midair, location.

[Hughes]

No luck yet, but I will try to understand POVray a bit more and then hopefully come up with a solution. Many thanks for your help and will let you know if and when I succeed!

[Hughes]

It turns out there is no need for anything more complex than just trying out different strengths and positions of the lights!

Here is the result. It can still be improved, but it is more or less what I was aiming for.

   

[Roland Melkert]

It turns out there is no need for anything more complex than just trying out different strengths and positions of the lights!

Here is the result. It can still be improved, but it is more or less what I was aiming for.

Nice.

You might improve things more by playing around with area lights instead of the plain ones.

[Rene Rechthaler]

would the studio way also work for that (assigning luminance to bricks/elements itself)?
-> there are special render-only colors with variable luminance/brightness

[Roland Melkert]

would the studio way also work for that (assigning luminance to bricks/elements itself)?
-> there are special render-only colors with variable luminance/brightness

Studio uses a cycles fork (blender) for rendering, so if you want the same results you probably better of digging (Deep) into blender editing.

There is a LDraw import plugin for blender and LDCad offers a glTF export you could also use to import into blender.