Hello hokiecsgrad, there are three objects in that scene.
A plane with a checker pattern. The plane is translated by (0, -10.1, 0). The pattern itself is also translated by (0, 0.1, 0). The 0.1 avoids pattern "acne".
Then there is a glass sphere. It's just a unit sphere placed in the origin so there is no transformation at all. Material is supposed to emulate glass, it's set to: diffuse=0.1, shininess=300, reflective=1, refractive=1, index_of_refraction=1.52.
Finally, there is an air sphere inside the glass sphere. It's just another unit sphere scaled by (0.5, 0.5, 0.5), i.e. half size. It has the same material parameters as the glass sphere except for index_of_refraction=1, i.e. that of air.
A point light is placed at (20, 10, 0), intensity is 0.7.
The camera is placed at (0, 2.5, 0), looking towards the origin (0, 0, 0) and field of view = pi/3.
Ascotti, I really appreciate you posting your setup, I was having trouble producing good results. The following image shows what I get with your setup.
Notice that I don't get the whole sphere in the picture nor is it as bright as yours. Also the specular highlights are different, but you didnt specify the specular value so I used 0.5 which could explain that difference.
I triple checked the numbers you gave, any idea why the differences?
I'd have to see your code to do more than guess, but at a guess, I'd say that either your field of view isn't be computed correctly, or you're closer to the subject than you think. For the plane, I wonder if your checkered plane needs a higher diffuse value, it seems pretty dim.
But the fact that you're getting the proper refraction effect is a great sign! That's generally the hardest part of this particular exercise. Congrats!
I just reproduced your Table scene by hand-coding the yaml you posted and I got a picture perfect result, so I think the fov is probably working properly. Also, I think it also indicates the lighting is good, it seems lit very much like yours.
So its still a mystery to me, I will quadruple check his setup.
manxome -- you know, I feel silly for not seeing this earlier. I think the reason you're not getting the whole sphere is that you're using a different aspect ratio than the original. The original is using a 1:1 (square) aspect ratio, but your image is rendered with 16:9 aspect ratio. If you set the width and height equal, I suspect you'll get an image that at least fits the entire sphere like it should. It still doesn't answer to why the image is so dark, though.
jamis, I am feeling pretty silly myself! ascotti left out a number of parameters which I guessed at and I think I made the pattern too dark, doh! Fixing the width & height, and brightening up the floor pattern a bit yields
I am curious about the internal shadow I see in ascotti's image... Thanks again! I doubt I will ever make that width & height error again