Interior lighting issues

[rkulshrestha]

I tried to do a simple interior lighting project as an experiment and am attaching the ksp file, screenshot and rendered image.
I have the following questions:
1. Why do I have a blowout on the left side?
2. Why do I have speckles?
3. There is a separate bulb in the ceiling lights. The cover has milky white material and the bulb itself has IES light. why is the light spreading on the ceiling?
4. Why are there unwanted white splotches on the walls?
5. Why is the floor lamp spotlight falling on the floor, it is perfectly centered in the 3D model on top of the coffee table.
6. Why is the wattage setting at .005 and not a regular 20 to 100watts?

Shivani

[rkulshrestha]

Nothing like holidays to motivate you to play with KS!

I did another render experiment and the result are far better. Now plan to duplicate the ceiling lights and see the over effect. Havent added environment or backplate as yet. Speckles still show up.
I re-did all the lights carefully this time. Named each part as the body, cover and bulb. So the body gets painted black, the cover a grey glass basic and the bulb takes the light material.

I have 4 lights types here, Fireplace, Floor Lamp, Ceiling Light and Outside (Porch) light ( which has not been lit up in this image). Strangely, the watts I am applying are in the range of .0005 to .1 watts. Don't know why. The back wall picture was enhanced using emissive light.

There is considerable difference between a screenshot render and a real render. So I had to go step by step, first illuminating the fireplace, then the floor lamp, then the ceiling lights and now I will do the Porch lights next time. Each time I set up a light I did a render to see the effect, then move on to the next light. I chose to start with the smallest lights, starting with the largest lights would presumably drown out the effects of the smaller lights.

There are too many lights to choose from and impossible for me to remember which light I used, so it's a good idea to create a new material folder (Favourites or some such) and duplicate the lights you use into it)

Applying materials in the standard docked windows is a hassle. So I would drag the right side window next to the left side window. This brings the materials window closer to the scene tree. Once finished, I enable window docking to get the standard layout again. But this really helps to avoid painting material over the wrong surface.

The scene tree was really important. Its good to move all the lights to a separate folder and separate folders for separate lights. In the image below, I will now duplicate the ceiling lights into new positions and this helps with the working of it all.

The outline works only when the scene tab is activated. I didn't know this, so took some time to discover this feature.

I am attaching the KSP file for anyone who wants to play with it. We really need some good tutorials on interior lighting.

For those who know all this, no apologies, I came back to KS after a long time and am on the path of rediscovering this amazing piece of software. This post is meant for all those who don't know

Shivani

[rkulshrestha]

I was trying to see the effect of caustics enabled on the red vase. For some reason, if I enable caustics the ceiling lights flare up and become a splotch of white. Just writing up my experience for future reference instead of keeping a journal! And maybe it will help someone.

[rkulshrestha]

I don't have a front wall so light is probably pouring in from the camera side. Debating whether I should have a fully enclosed room for a better effect.

[rkulshrestha]

I know I'm going to forget this. The modular lights once applied always seem to point in the wrong direction. You have to use the move tool on the bulb to rotate them to the right direction. Here's another image rendered for 20 minutes. The ceiling lights are not perfect and the floor is washed up now. I think I have to increase roughness on the floor. The speckles won't go away.

The second is a screenshot with caustics enabled.

[rkulshrestha]

For the floor just reduce brightness from the texture tab.

[Rex]

Hi rkulshrestha,

Thanks for sharing your thoughts and process. The wattage values are so low because your scene is set to use Inches while it looks like your model was created in meters. Try changing the scene units to meters in the edit menu and adjusting the wattage values accordingly.

[jhiker]

I don't have a front wall so light is probably pouring in from the camera side. Debating whether I should have a fully enclosed room for a better effect.

I may be wrong but I think I saw a tutorial that demonstrated the interior mode works best when the scene is enclosed, i.e. four walls and a ceiling. If you have a wall missing it might affect the 'interior mode' rendering algorithm.

[rkulshrestha]

Wow, Thanks Rex, I won't have spotted that in a thousand years! I think I will redo this.

Thanks Jhikers - will take your comment on board and include the suggestion in my next attempt.

I do wish there was a way to get more feedback on how to improve this simple scene. The interiors community is a large one and Keyshot would be a great product for them. It would be nice to have people play with the attached KSP's, improve on it and post the results as an educating mechanism. Same thing with all the Youtube videos, it would be great to have access to the associated KSP files so that we can try and duplicate the tutorial.

Cheers

[Will Gibbons]

I just opened your 2 KSP files. A few things I see to be mindful of.

1. Your scene is about .01"x.01"x.01", and the other is less than .5"x.5"x.5". It is so small that the light is not behaving normally (also why you need to turn the muliplier down so low)
2. The scale will also affect your textures and the scaling there.
3. An interior renders best with interior lighting mode.
3.1. For interior mode to work properly, you need a watertight space (glass on window) and no missing walls/ceilings.
4. Some of your materials have been set to the default of 'diffuse' material type, which won't behave naturally. Try changing to other material types.
5. IES profiles are directional, whereas area and point lights are not. (sounds like you may have discovered this)
6. Try keeping absolute black and absolute white out of your materials and light by not using pure white or black for any values. This helps to avoid hotspots.
7. Increase material samples in areas that need further refinement.
8. Using corresponding bump maps for areas that you wish to texture will help cast proper highlights and shadows.
9. Use roughness to cut down on glossiness of materials, which should help reduce areas of over-reflectivity.
10. If your rendering is not looking like it does in the realtime view, try using max samples or max time instead of advanced render settings.

These should help you with your interiors.

[rkulshrestha]

Hi Will

Thanks for responding, been through a few of your tutorials!

I have googled and read every article on scaling in Keyshot before responding to your post. I have a few questions:

1. How did you figure out the size of the models.

2. My model in SketchUp is 650cm x 460cm. When I export that the scale should not be reducing by such a large factor (5"x5"x5").

3. What should be the ratio of an environment to the model. How do I determine the height and size of the environment in relation to the model. The height and size are adjustable parameters.

4. After experimenting a lot, I decided to use a the HDRI you see below. I adjusted the scale using the trees in the background as a reference. (environment scale.jpg). I scaled up in all directions by a factor of 10. Did not adjust height or size of the environment.

5. I the set the scale units to inches and measured the vase position from the left side to right side (position images). This works out to 116" or 295cms, still short of the 462cms.

6. Then I lit up the ceiling light and had to bump it up to 5000Watts to get a little twinkle of a light.

Appreciate if you can give me some more guidance.

Cheers

[rkulshrestha]

Also posting the bip file, just in case.

[rkulshrestha]

OK got somewhere. Clicking on the full model in the scene tree gives the full model size in inches.

[Will Gibbons]

Hi Will

1. How did you figure out the size of the models.

2. My model in SketchUp is 650cm x 460cm. When I export that the scale should not be reducing by such a large factor (5"x5"x5").

3. What should be the ratio of an environment to the model. How do I determine the height and size of the environment in relation to the model. The height and size are adjustable parameters.

4. After experimenting a lot, I decided to use a the HDRI you see below. I adjusted the scale using the trees in the background as a reference. (environment scale.jpg). I scaled up in all directions by a factor of 10. Did not adjust height or size of the environment.

5. I the set the scale units to inches and measured the vase position from the left side to right side (position images). This works out to 116" or 295cms, still short of the 462cms.

6. Then I lit up the ceiling light and had to bump it up to 5000Watts to get a little twinkle of a light.

Appreciate if you can give me some more guidance.

Cheers

1. Looks like you figured this one out.

2. I've noticed that Sketchup models can come into KeyShot at an odd scale. I'll follow up with someone else at KeyShot to see if I can pinpoint the reason for that. In the meantime, sit tight. Maybe a workaround is to calculate the factor that it's being scaled down by and scale your model up by that same factor in Sketchup before importing into KeyShot so it may be scaled down to the size you want. See if that works until a better solution is found.

3. The Environment (I assume you mean HDRI) in KeyShot should be quite a bit larger than your model. If you're doing an interior and using the Sun/Sky HDRI, I'd make the environment about 10-20x larger than your model. Just eyeball it.

4. Your environment should be about 10x larger than you have it there. An HDRI is never intended to be used as a background, rather as a light source. You can go ahead and use a totally different (higher-resolution) backplate in conjunction with an HDRI to create the 'environment' you want to.

5. Be careful when changing units within KeyShot as whether you convert or correlate has very different effects on the KeyShot scene. Ideally, I'd handle all scale/unit conversion within your 3D app (Sketchup in your case).

6. Watts in KeyShot are not the same Watt unit used on lightbulbs. Use either Lumen or Lux is my recommendation. For reference, a 100w Lightbulb is equal to 1600 lumens.

Let me know if any of that helps.

[rkulshrestha]

Hi Will

Thanks for the response, all of it helped and I am on to my second experiment. 

This is a model from http://www.sketchuptexture.com/ which is a great community for free models and textures.

All the advice you gave helped reduce the effort in rendering this model and I am attaching the first draft.Mot everything has material applied to it as yet cos the first thing I'm trying to do is get the lighting right.

I need some advice on the ceiling lights. I get this hallo around them and a black spot in the centre. Any advice on the best way to construct a ceiling light and which materials are the best to apply to which component to get a realistic render?

The SU model is above 50 MB as is the Bip and KSP otherwise I would have posted it.

Thanks in advance.

Raj