Create clouds in autocad 2011

[DAMO]

Hi All,

 

I use Autocad 2011 for my renderings. You can use the sun and sky & Illuminations settings. It works just fine.

 

BUT....

 

I want some clouds in the sky, and when i choose for background, there's no sun! So who knows/wants to find out, how to create hem both!?

 

DAMO

[Cad64]

You might want to take a look at this: http://www.dscohn.com/AU/handouts/GD115-2%20Rendering%20part%202-DOC.pdf.

Scroll down to about the middle of the document.

[DAMO]

Hi,

 

I know this document, and it's not what i mean. I know you can use a foto for the background. See, my previous project:

 

But i want to try and create clouds in this picture:

 

 

I'm thinking about half a dome that's transparent and has a few clouds on it...

[Cad64]

It still works the same way, whether you're viewing the background through a window or if you are out in the open: http://www.google.com/imgres?imgurl=http://www.we-r-here.com/cad_07/tutorials/level_3/images/background.gif&imgrefurl=http://www.we-r-here.com/cad_07/tutorials/level_3/3-17.htm&h=383&w=342&sz=19&tbnid=8uQlmE0qP8OklM:&tbnh=123&tbnw=110&prev=/images%3Fq%3Dautocad%2Bsun%2Band%2Bsky%2Bwith%2Bbackground%2Bimage&hl=en&usg=__rxI2rDpULN-Ko60u9axDZE-4Ehw=&sa=X&ei=74I7TL3UD4XWtQOY-LDaCg&ved=0CCEQ9QEwBA

[DAMO]

Okay,

 

if that's it, I'll try that first!

 

Thanks!

[DAMO]

Okay,

 

I tried to do what you said, but don't forget, I work on AutoCAD 2011, and there's the function of the sky and the Illumination of it. This works perfectly when no background is selected.

 

 

But when a background is selected I got this:

 

The sun is working, but the illumination is not!

[iskalipsi]

I think you placed your sun in the wrong place...

[DAMO]

Why, in the image a few posts back the sun is good, it's the same camera view, only with a background in stead of the sun & sky background...

[fahim108]

Well, you're right Damo. Background images and sky lighting don't go hand in hand.

 

But again, there is a workaround. You can use any image editing software (like Photoshop) to add the sky and other backgrounds AFTER you have rendered the scene. To make things simpler, let me present a way to do so...

 

1. Render your scene with Sun and Sky lighting (indirect illumination) turned on. Save the image.

 

 

2. Now, turn OFF Sun and Sky lighting.

 

3. Type in RPREF (Advanced Render Settings), turn OFF Shadows, Ray Tracing, Indirect Illumination, Final Gather.

 

4. Render the scene.

 

 

5. Save the image as a PNG - with 32 Bits (24 Bits + Alpha) option checked.

 

6. Open the first image in Photoshop and use the second image (which contains Alpha information) as its Layer Mask. It would look like this...

 

 

7. Now use your "cloudy" background under this layer. :wink:

 

 

8. Done!

 

Note that it even works for transparent materials (as the window on the right side).

[iskalipsi]

Nice tip there fahim. deserves a star! I'm not very good in photoshop, why do you need the second image as its layer mask?

[fahim108]

...why do you need the second image as its layer mask?

To add transparency! ...lol.

 

Basically, the program uses the alpha channel of the second image and applies it on the first one. This way, the default Sky background (that you see when rendering with Sky Background and Illumination option checked) can be replaced by any image of your choice without manually selecting and deleting areas... note the level of smoothness you get at edges!

 

If you save the first image as 32 Bits PNG, you won't observe any transparency. This is because it has already been flattened by AutoCAD while rendering the sky background.

[DAMO]

Hi Fahim,

 

This is a excellent trick! I thougt of it when seeing the option 32bit, but there was no alpha Step 2 was the answer for that difficulty.

 

i'm going to try that and show the result here!

 

Thanks again!

[fahim108]

I'm glad it helped!

[sevdo2000]

Hi Fahim. Can I ask you something about FS. When I use mask like you - disapears the house, background and shodows remains? How do you invert that to disapear only background

[fahim108]

That's strange. Either the background should get transparent or the foreground. The shadows are just a part of the foreground, so if you see shadows, you should see other stuff too.

 

I am pretty sure you are doing something wrong here!

[sevdo2000]

So, I'm starting with that:

 

Then I'm rendering like you said without some options:

 

And when put mask 2 to pict 1 it becomes:

[fahim108]

Well, I used PaintShop in my earlier post and it has this option where you can chose the source opacity and even invert the mask data:

 

Do you have a similar option there in PhotoShop. If yes, then use the settings that I have highlighted. It works here... everytime!

[sevdo2000]

I guessed there is an option to invert mask, but I did't know where is that. My PS is CS3. I'll search know better in Google for "Add mask from image" (top of your option window - now I know) - thanks.

[busseynova]

In Photoshop:

 

Press Ctrl and click on the alpha mask to select area, this will select the area with rendered objects within it, so then press 'Ctrl + Shift + I' to invert the selection. Then delete to clear the transparent/background area.

 

This thread is great, after reading the other day I tried inserting a background into a render for the first time. Came out ok, and much easier and more effective than using the ACAD image background.

 

I actually went to quick-mask in PS and used 'image > adjust > brightness/contrast' to ajust the selection slightly as I hadn't got the transparency of my glass quite right. Here's the final result, pretty crude but a good start anyway:

[fahim108]

That's whats I am talking about! :wink: ...you can post-process the background after the rendering, isn't that great.

Just a tip: Try increasing the brightness (exposure) of that background image. It would look more realistic. Simply, google for some interior pics, then observe the "white windows" and you'll know why I am talking about.