point light

[Oshyan]

Wow, excellent detail! Can't wait to see a finished render.

- Oshyan

[old_blaggard]

Looks great!  If you're so inclined, we wouldn't mind having that file in our repository over at www.ashundar.com.

[lonewolf]

Thanks guys. It's my first go at a proper 3d model. I made it in Google Sketchup.
Here is the picture I used as a reference.

Iain

[rcallicotte]

Wow, great model and great potential.

[JimB]

Been working on my new lighthouse. This one has a hollow lightbox in the top for my pointlight to go in.
Initial render of the object tells me I have to work on the shaders a little, but most of the detail I wanted is there.
When I get it right, I will be making a day image and a night image.

Iain, that's a really nice model. Good job!

On another note, I think there's a classic CGI lighting problem here, and a soft shadow sun should possibly be used. It's when a curved surface with a specular material is strongly lit from one side, and what you see is that incredibly strong contrast between light and dark running the height of the lighthouse, instead of the division being slightly blended as the light curves around (the Sun is a big sphere of light that wraps light around objects, not a singularity). It's something Planetside should be aware of. I always use an area light as a sun when creating 3D environments for jobs. That way, the light wraps around slightly to get around that hard cut-off contrast issue. It's usually not a model resolution issue either. You can see what I'm talking about if you compare your render to the photo of the real lighthouse.

If it's any consolation, Renderman used to do it which I found out on a job involving a white space rocket a number of years ago, and I ended up coming up with the above solution in Mental Ray. 

I'm also not taking anything away from your render, please understand. It's just a CGI thing. Hope I'm not hijacking the thread. 

[rcallicotte]

Jim, does this mean using something beyond the soft lighting provided in TG2?

[JimB]

Jim, does this mean using something beyond the soft lighting provided in TG2?

I've no idea, but I'd recommend playing with specularity to try and keep the spread of the highlight down.

Just to add, I think the best way to illustrate what I'm talking about is by looking at photos of Earth from space, noting how the division between day and night is soft, not very hard:
http://www.harmsy.freeuk.com/images/earthmoon.jpeg
http://hyperphysics.phy-astr.gsu.edu/hbase/solar/picsol/earth5.jpg
http://chamorrobible.org/images/photos/gpw-200702-75-NASA-ISS002-E-7377-space-ocean-terminator-night-and-day-20010617-Earth-medium.jpg
http://www-misr.jpl.nasa.gov/education/images/Apollo8_Earth2.jpg
http://www.dkimages.com/discover/previews/794/976497.JPG

[rcallicotte]

Thanks, Jim.  I'm learning lighting and this helps.

[Will]

Nice, I can't wait to see how this comes out, a lot of interesting lighting going on here.

[Matt]

Hi Jim,

I agree with your observations about the hard edge on the terminator of hard surfaces and how they can be improved by using an area light, but I think the Earth images show something different. In those Earth terminator images most of that softness comes from the scattering effects of the atmosphere. The angular diameter of the sun as viewed from the Earth is only about 0.5 degrees, so on a hard surface there is only about 0.5 degrees of additional softness that wouldn't be there with a point light source.

Enabling soft shadows in TG2 may help to slightly soften the terminator on hard surfaces, but it doesn't simulate all the softening effects you'd get from a true area light source. Not yet anyway.

Matt

[rcallicotte]

Hmmm.  Mmmm, hmmm.  Interesting. 

Not yet anyway.

Matt

[Mr_Lamppost]

Nice model 

I know you are duplicating it from the photo but what is all that shoreing up around the base?

Looks great!  If you're so inclined, we wouldn't mind having that file in our repository over at www.ashundar.com.

Didn't expect that  then "Nobody expects the Spanish Inquisition" 

I agree with your observations about the hard edge on the terminator of hard surfaces and how they can be improved by using an area light, but I think the Earth images show something different. In those Earth terminator images most of that softness comes from the scattering effects of the atmosphere. The angular diameter of the sun as viewed from the Earth is only about 0.5 degrees, so on a hard surface there is only about 0.5 degrees of additional softness that wouldn't be there with a point light source.

Enabling soft shadows in TG2 may help to slightly soften the terminator on hard surfaces, but it doesn't simulate all the softening effects you'd get from a true area light source. Not yet anyway.

Matt

I am sure you mentioned elsewhere that the GI does not take account of secondary forward scattering of light in the atmosphere, which I guess is at the root of this problem, not confined to TG. 

[Will]

heh I just realized your modeling a model

[JimB]

Hi Jim,

I agree with your observations about the hard edge on the terminator of hard surfaces and how they can be improved by using an area light, but I think the Earth images show something different. In those Earth terminator images most of that softness comes from the scattering effects of the atmosphere. The angular diameter of the sun as viewed from the Earth is only about 0.5 degrees, so on a hard surface there is only about 0.5 degrees of additional softness that wouldn't be there with a point light source.

Enabling soft shadows in TG2 may help to slightly soften the terminator on hard surfaces, but it doesn't simulate all the softening effects you'd get from a true area light source. Not yet anyway.

Matt

Good point Matt. However, we don't see a harsh terminator on planets without atmosphere. I personally put it down to the Sun being much larger than any of the planets, which means light is hitting the 'spheres' from a wider source and wrapping around slightly. I've used the technique before and you get two desirable things; a soft division between the day and night side, and a more even spread of light on the day side which smooths out the distribution of light. The latter means you don't get a very harsh polarisation of light where the planet's surface is pointing more directly towards the Sun, which we see in actual planetary photos (it was one of those things that always bugged me about singularity light sources).

That 0.5 degrees makes a big difference because the surface area being illuminated is actually quite large.

I did a very quick test in TG2 last night and you are definitely correct that the Atmosphere is diffusing the light and softening the terminator. However, if you have clouds that are very (and unrealistically) high they show a harsh terminator, possibly because of the scattering which might be similar to specular shading?

I think my point is, more importantly, that when applying a specular surface, be wary of making the specularity too rough and tweak it. Far better to use proper soft reflections with just a little bit of specularity thrown in. There are CGI lighting techniques that can throw out ambient occlusion and final gathering completely by using soft reflections only.

[nikita]

Good point Matt. However, we don't see a harsh terminator on planets without atmosphere.

But that's not due to the sun being an area light. It's more or less the small structures that throw longer shadows when they are nearer to the dark side. So, shadows get more frequent the closer you get to the day/night-border. When watched from the distance, you don't see the single shadows, but an overall darkening effect that results in a seemingly smooth transition from night to day side.
The effect can be seen on this photo: http://www.lighthouse.net.au/Lights/TAS/Cape%20Wickham/Cape%20Wickham%20Tower%20rc%203.jpg

That being said - if the lighthouse had a rough but subtle surface, that might do the trick.
(IF its walls are made of stone)