topic Re: New Material, Bump Map? Alpha Channel? in Visualization

New Material, Bump Map? Alpha Channel?

Chris Grantham — Thu, 11 May 2023 10:10:52 GMT

I am trying to develop a new lapped large metal panel siding material, and I am wondering about getting some relief to appear when I render it. I am a bit confused about Bump Map/Alpha Channel. Is this something I need to do in photoshop before loading the image. I feel like every article I read says something different. Does anyone have any tried a true methods for this? I have attached an image of what I would like the final product to look like. Thanks!

-Chris

Re: New Material, Bump Map? Alpha Channel?

Dwight — Sat, 16 Oct 2010 22:23:50 GMT

I assume that you want to create this as an image......

It's confusing because different methods relate to the different ways applications derive depth effects.

For instance, in the old Archicad days, "bump maps" used the edges of alpha channel images to produce the fake shadows we interpret as depth. You'd make such an alpha channel in Photoshop by selecting the shadows in the texture's photo image, create a mask [aka alpha channel] and save the image in a file format supporting alpha channels like tif or psd - NOT JPEG!!!!!!

Today, applications like LightWorks use two methods to build the illusion of depth:
— they automatically use the greyscale values in the image's red channel to build depth effects.
— they import another image, specially prepared, that precisely creates the edges of the depth effect. When the application sees this image, it substitutes it for the red channel info.

So, yes, you need to create the depth information in Photoshop.

To learn this, create a white image field, add an alpha channel, and draw something in this channel. Use black lines and gradients.

Use this image to texture a plain colored material, say red. When you import the image, it will be white - you won't see the alpha channel info.

Select 'bump' for the alpha channel effect.

When rendered, the bump will appear as relief on the material surface.

You can vary the degree of depth by using greys in the channel, say, to create rounded edges.

It is the sort of thing you need to experience as an artist.....

Re: New Material, Bump Map? Alpha Channel?

Chris Grantham — Tue, 19 Oct 2010 16:36:04 GMT

I am starting to get my head around this... I think. How do I get it to appear properly in my OpenGL model? It seems like it is one or the other (lightworks/internal engine or openGL).

Re: New Material, Bump Map? Alpha Channel?

Dwight — Tue, 19 Oct 2010 17:23:11 GMT

For a beginner, use the old dialogs to create the new material and switching to LightWorks, use "Match Internal" where it absorbs the internal engine settings.

Re: New Material, Bump Map? Alpha Channel?

Chris Grantham — Tue, 19 Oct 2010 17:35:41 GMT

I started off with a previously created material, and added a new image. Here is my current set up. Included are my photoshop image which I copied one in the textures library, and loaded it as suggested that way I do need to reload each time. I also included settings for the different rendering engines. I still feel like I am fumbling around like an idiot tho...

Re: New Material, Bump Map? Alpha Channel?

Chris Grantham — Tue, 19 Oct 2010 17:36:42 GMT

Internal Engine

Re: New Material, Bump Map? Alpha Channel?

Chris Grantham — Tue, 19 Oct 2010 17:37:51 GMT

Open GL Note the Preview shows no texture?

Re: New Material, Bump Map? Alpha Channel?

Chris Grantham — Tue, 19 Oct 2010 17:39:09 GMT

Lightworks

Re: New Material, Bump Map? Alpha Channel?

Anonymous — Sat, 23 Oct 2010 17:53:21 GMT

Chris wrote:
Open GL Note the Preview shows no texture?

This is probably due to your 3D window settings.

Why are you showing us all the settings dialogs? Do you have any specific questions? Just so you know this stuff is tricky, meticulous and time consuming even for us experts. (Yes, reloading the textures every time you edit the source is annoying.)

I assume you know that the only way to really see what you are doing is to set up and render (and re-render, and re-render) a vignette in the 3D window. The preview is close to useless.

BTW: Do you have Dwight's book? It's a big help with this stuff.

Re: New Material, Bump Map? Alpha Channel?

Chris Grantham — Sat, 23 Oct 2010 19:25:55 GMT

See Matthew, you answered my question! I did not even think to look at my 3D window settings. DUH. I guess I just posting how ended up answering my initial questions, thanks to the help of Dwight, both personally and his book. Long story short... forget lightworks, get artlantis. I got the desired effect in about a 10th of the time.

Re: New Material, Bump Map? Alpha Channel?

Chris Grantham — Sat, 23 Oct 2010 19:25:56 GMT

Re: New Material, Bump Map? Alpha Channel?

Dwight — Sat, 23 Oct 2010 19:52:26 GMT

Artlantis is a best-buy for productivity exporting from Archicad, altho there are many less expensive alternatives. Artlantis has acceptable simplicity, quality, entourage and speed.

Even though I wrote the LightWorks book five years ago when it was first introduced, Graphisoft's implementation has always been deficient compared to the way LightWorks COULD work and in the intervening years has improved little.

I encourage all Archicad users to get Abvent's free, fully-featured trial and experiment with Artlantis to see for themselves. And, of course, my book.