Glass problem

Glass problem

Hi,

Certain things about this program are quite frustrating to figure out.

I have a plane of glass that I made from a box and applied my material to it. In the working environment I can see through it but when I render it I can't. What's up with that?

The same thing happened to my SU material when I imported the model so I built a new plane of glass hoping to solve the problem.

Hmm I seem to have the reverse problem (I'd like to be able to see through textures in the work environment )

I think you're seeing a refraction problem because you're using a plane instead of a very thin cube (or similar). Basically the light ray goes through the plane and thinks it's entered a glass universe and gets bent in a direction that hits black.

(See attached image.)

As far as any light rays passing through the planes are concerned, either they have entered or exited a universe made of glass.

So... how do you make transparent textures show as transparent in the work environment? It's bugging the heck out of me.

podperson said:

Hmm I seem to have the reverse problem (I'd like to be able to see through textures in the work environment )

I think you're seeing a refraction problem because you're using a plane instead of a very thin cube (or similar). Basically the light ray goes through the plane and thinks it's entered a glass universe and gets bent in a direction that hits black.

(See attached image.)

As far as any light rays passing through the planes are concerned, either they have entered or exited a universe made of glass.

So... how do you make transparent textures show as transparent in the work environment? It's bugging the heck out of me.

Click to expand...

I'll trade problems! I have no idea how to make it like that in the work environment? My glass is made from a cube object - even so the glass I made in Sketchup originally did the same thing.

Hmm -- I don't see the same problem, and I doubt you've been fiddling with render settings. Try selecting the window pane (make editable if necessary) and then select all the faces and invert their normals. See if that has any effect.

Oh -- what have you set refractivity index to? Try 1.3 or so if you haven't.

Oh and everything except emission should be set to white with transparency ~0.95.

podperson said:

Hmm -- I don't see the same problem, and I doubt you've been fiddling with render settings. Try selecting the window pane (make editable if necessary) and then select all the faces and invert their normals. See if that has any effect.

Oh -- what have you set refractivity index to? Try 1.3 or so if you haven't.

Oh and everything except emission should be set to white with transparency ~0.95.

Click to expand...

Okay I'm trippin out here! I just made a box in the middle of the room and applied the "same" glass material to it and it works perfect! But my other box doesn't? Is it becase I applied the material after I sized the box? No...it couldn't be !?!?

If you sized the glass down to the point where it was "negative" in size it will have all its normals flipped.

(Edit: I just checked and even having the normals flipped shouldn't be causing that problem.)

Attached is another image. The top pane has its normals flipped. You can see a subtle difference, but it wouldn't cause the problem you're having.

Also shown is my edit view -- note that the glass panes are opaque in the editing environment for me (both on my G4 iBook and my Mac Pro with a 7300 -- nVidia problem?)

podperson said:

If you sized the glass down to the point where it was "negative" in size it will have all its normals flipped.

Click to expand...

Hmmm, I don't understand what a normal is but Ill make a new box and try and size it carefully.

From the online help (better than the definition I started typing):

In 3D programs every polygon has a "normal" pointing directly out from its surface. By convention, the "normal" points "out" from the polygon when you view it from the side where its edge run counter-clockwise (and "in" to the polygon when you view it from the other side). For various reasons, by convention polygons aren't rendered from the reverse side ("back face").

A "glass" object has outer faces with normals pointing outwards, this way the renderer knows it's "inside" the glass when a light ray passes through an outward facing polygon, and "outside" the glass when it passes through an inward facing polygon.

By default, Cheetah3d doesn't light back faces so the top pane in my view is darker. In many 3d programs polygons are invisible when viewed from behind.

(If you've worked with 2d drawing programs like Illustrator, polygon winding direction and "normals" are the 3d equivalent of "winding order" with Postscript -- a way for a program rendering an image to know when it's "inside" and "outside" an object.)

I hope this makes sense. If I were thinking more clearly I could probably give a shorter and clearer explanation.

Kinda, thanks I'll have to read up on it some more.

This is frustrating the hell out of me though. As soon as I resize the cube to be glass size and move it into place it is opaque. I thought it might be lighting so I put a light outside and it still didn't work.

I'm giving up for now, I've spent 4 hours trying to figure this out.

Thanks for your help Pod.

I know what it is now just not how to fix it.

The clouds are loaded into the "camera" background and when the glass is in place for some reason you can't see the background anymore. I made a wall out behind the glass and applied the cloud jpeg to it's surface and you could then see the clouds through the glass. Someone may know how to do this with the jpeg in the camera background slot?

Thanks.

podperson said:

So... how do you make transparent textures show as transparent in the work environment? It's bugging the heck out of me.

Click to expand...

Hi,
What you do is click the color swatch in the Material settings window and set the opacity down about half way.

Greg

Don´t give up - take a break;-)

Hi.
I understand why it is frustrating, but again I can´t reproduce this kind of behavoir. It has nothing to do with "flipping normals". BTW; getting flipped normals more visible go "style->light both sides".

So if in doubt, send it to Martin and he will check it it up. From here it is a carrepair through a telephonewire - no chance.

What you do is click the color swatch in the Material settings window and set the opacity down about half way.

Click to expand...

Good tip, Greg

With kindest regards
Frank

Innerdreamrecords said:

Hi,

Certain things about this program are quite frustrating to figure out.

I have a plane of glass that I made from a box and applied my material to it. In the working environment I can see through it but when I render it I can't. What's up with that?

The same thing happened to my SU material when I imported the model so I built a new plane of glass hoping to solve the problem.

Click to expand...

Hi,
A quick fix is to remove the clouds from the camera. Make a plane object and attached the clouds as a texture and use that as the background.

One problem with importing from SU is that it can create multiple faces for the same object and some can have there normals flip so this could also be adding to your problem. There is a post of the forum regarding this issue, somewhere.

Andrew

P.S. Another way of having the sky as a background is by removing the sky from the camera, add a hdr tag to the camera and have the sky image set as panorama in the hdr tag properties.

fused said:

Hi,
A quick fix is to remove the clouds from the camera. Make a plane object and attached the clouds as a texture and use that as the background.

One problem with importing from SU is that it can create multiple faces for the same object and some can have there normals flip so this could also be adding to your problem. There is a post of the forum regarding this issue, somewhere.

Andrew

P.S. Another way of having the sky as a background is by removing the sky from the camera, add a hdr tag to the camera and have the sky image set as panorama in the hdr tag properties.

Click to expand...

Andrew thanks.

I made new glass in Cheetah so I believe this is a problem with the way the "background in camera" function works. I put up a "plane" in the verticle direction like you said and applied my clouds and that works but in other scenarios I can see this as not being a good solution. I'm going to try and add the clouds to the "hdr tag" as you suggested.

To continue on about this frustration, is anyone planning a good book on this program? I've watched the video tutorial's recommended here and read tons and the learning tools are slim at best. In my opinion Ted Boardmans series available from his web site on how to build a house in 3D Studio are so clear and well put together I would like to know if such a thing exists in Cheetah land?
This is a really good renderer/modeler as far as I can tell but lacks certain basic information in the "manual" department.

Okay this really sucks. The HDR tag does not work well at all as a panorama using a straight jpeg - perhaps a proper hdr image will work better. So far the only thing that has worked is to build a wall on the horizon and apply the jpeg. I'll be honest here I work in a highly demanding environment and this kind of solution will not suffice for the kind of work we're doing.

Does anyone know how to make this happen in a good way, not a band aid?

Thanks for everyone's help.

Here's a thread that covers a similar problem, I think it will help.

http://www.cheetah3d.de/forum/showthread.php?t=837&highlight

Good call, fused. In particular, the last paragraph of reply #8 explains the issue well. For now you could pad your jpg to fit a panorama as the above thread suggests, but if you're doing a lot of work with outdoor scenes, it would be worth it to invest in a good sky HDRI or two.

I think the short answer as to why the Camera Background doesn't work is that it doesn't interact with the scene, just gets matted behind any empty pixels.

Innerdreamrecords said:

Okay this really sucks. The HDR tag does not work well at all as a panorama using a straight jpeg - perhaps a proper hdr image will work better. So far the only thing that has worked is to build a wall on the horizon and apply the jpeg. I'll be honest here I work in a highly demanding environment and this kind of solution will not suffice for the kind of work we're doing.

Does anyone know how to make this happen in a good way, not a band aid?

Thanks for everyone's help.

Click to expand...

Dear Innerdreamrecords

You have to use .hdr files to get best from that tag jpgs will give you a halfway decent solution, try some of the free .hdr files like the sample ones with the program. and maybe add a few fill in lights to enhance the result...it's all a matter of doing a few tests and saving the results you like. Also the help files for the program are really good, check out the materials settings on glass


Regards

Luke

fused said:

Here's a thread that covers a similar problem, I think it will help.

http://www.cheetah3d.de/forum/showthread.php?t=837&highlight

Click to expand...

From the thread, and thank you.

At this time, you can only use the HDRI tag with either a .hdr image or a .jpg image to do what you want.

Click to expand...

How this could not have been addressed in the camera view is beyond me.

Thanks Luke:

This is all I've found in the help files? Maybe I'm not looking in the right place? A
Material shader

The "Material" shader is the starting point for many types of materials. You can use it to map a texture onto a object but you can also use it for creating glasses or metals.

Properties:

Color: These parameters define the color of the material.

color: Color of the material.
texture: Color texture.
mix: Use this property to mix the color and texture values.
Ambient - Diffuse: These parameters effect the influence of the ambient and diffuse light components. For normal non reflective and non transparent objects these values should be 1.0. But for glasses and metals these values should be zero.

ambient: Scales the ambient light component.
diffuse: Scales the diffuse light component.
Specular: These parameters define the color and the size of the specular reflection. The intensity of the specular reflection can be controlled with the color or texture parameters. White means full intensity for all three RGB color components and black means zero intensity.

color: Color of the specular reflection.
texture: Specular texture.
mix: Use this property to mix the color and the texture.
size: Size of the specular reflection. Higher size values mean sharper and smaller highlights.

size=8
size=16
size=32
size=64
size=128
Emissive: The emissive component will be just added to the final material color. It doesn't interact with the lights in the scene.

color: Color value which will be added to the final material color.
Bumpmap: Bump maps alter the normal of a surface. This will not change the surface itself but it will change how the surface interacts with the light setup. Therefore the surface looks uneven under the light source but the surface is really flat.

texture: Defines the bump texture (bump map). A bump map is a grey scale texture where the white is for the maximum bump height and black is for no bump. These texture is therefore often also called height textures or relief textures.
intensity: Defines the intensity (height) of the bumps





intensity=0.2
intensity=0.4
intensity=0.6
intensity=0.8
intensity=1.0
Reflection: With these parameters you can define how strong the material will reflect the environment. A mirror for example will reflect the environment by 100%. The color of the reflected environment will be added to the material. Use the color and texture parameters to filter the reflected environment.

color: Filter color of the reflection.
texture: Reflection texture.
mix: Use this property to mix the color and the texture.
intensity: Intensity of the reflection. Due to the fact that the reflection will be added to the material color you have to downscale the material color or the diffuse properties to avoid over saturation.





ref intensity=0.2
dif intensity=0.8
ref intensity=0.4
dif intensity=0.6
ref intensity=0.6
dif intensity=0.4
ref intensity=0.8
dif intensity=0.2
ref intensity=1.0
dif intensity=0.0
angle: Use this propety to create blurred reflections. The higher the value the more blurred the reflection will become. Increase the samples property to reduce noise of blurred reflections.

angle=0
angle=5
angle=10
angle=15
angle=20
samples: Samples for calculating blured reflections. Render time will increases linearly with the number of samples.
Transparency: The transparency parameters are needed when you want to make transparent materials like glass. Increasing the transparency intensity automatically decreases the diffuse and ambient intensity to avoid over saturation. For creating colored glass (red glass for example) it is nevertheless recommended to set the diffuse and ambient intensity properties too zero.

color: Filter color for transparency.
texture: Transparency texture.
mix: Use this property to mix the color and the texture.
intensity: Transparency intensity.
index of refraction: The higher the index of refraction the higher the light will be bend while going through the material.
use alpha channel: Check this property on to use the alpha channel of the color texture for calculating the transparency.
fresnel: Check this on to add fresnel reflection to transparent objects.

Dear Innerdreamrecords

The hdr files see screengrab

and the was the bit I ment which helped me a lot in adjusting materials like glass

Reagrds

Luke