How to create realistic curtains for arch viz in Blender

Discover how to create realistic fabrics in the free 3D software, Blender! Filippo Veniero reveals his cloth-simulation techniques for more natural-looking arch-viz scenes

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If you use 3D software to create interior arch-viz scenes, sooner or later you're going to need to create a curtain. And yes, you can model it step by step – but if you use a cloth simulator you'll get very realistic results and save a lot of time!

In this tutorial I'll show you how to create a cloth and material simulation, and set up a simple interior scene. First of all, if we have a curtain then we are going to need a window too! Again: we could model a window, but why model something if there's an add-on to do that already?

Download window generator 2 from the forums and we'll use it later.

Step 1: Curtain setup

Open Blender, delete the default cube and add a plane; call it 'curtain' and set the shading to Smooth. Rotate the plane by 90 degrees along the X axis, apply rotation (Ctrl+A), scale to the size of 3 x 2 meters and move it 3 meters along the Z axis.

Jump to edit mode (tab) and subdivide twice (number of cuts = 10). Now your curtain has about 150,000 vertices – enough for a realistic cloth simulation. Select all the vertices now and unwrap (U > project from view); we'll use this information later.

In Object mode, add a plane and scale it 4 times (S > 4). Jump to edit mode again and subdivide once (number of cuts = 10).

Curtain setup

Curtain setup

Step 2: Selecting the vertex to be pinned

Select the curtain, open object data panel and add two shape key (Blender will add a basis and a key1 shape). Now jump to edit mode and select the vertex that will be pinned as show in the image below. Add a new vertex group, call it pinned and click on assign button. Move the 3D cursor on the first pinned vertex on the left side and set pivot point as 3Dcursor. Scale along x axis ( S > X > 0.5) and click on apply shape keys in edit mode button (in shape key panel with key1 shape selected). Now, if you click and drag value slide you'll see that the pinned vertex moves along x axis.

Pinning the vertex

Pinning the vertex

Step 3: Cloth simulation

In the shape keys panel, set the value at zero, move the mouse cursor to it and click 'I' ( Blender will add a keyframe), jump to frame 100, move value slide to 1 and add another keyframe. In the physics tab click on cloth, select denim, enable pinning and select 'pinned' vertex. Enable a self collision flag at level 2. Now it's time to save. Turn on disk cache, click on bake all dynamics and wait (coffee time).

At the end of the simulation click Alt+A to see the animation. We could make a more interesting animation moving the floor plane up along the z axis, so our curtain would be more realistic. Select the plane under the curtain and set as collision in the physics tab. Jump to the first frame, move the mouse cursor into 3D viewport and add a location keyframe ( I > location). Now, select the 50th frame, move just a little bit of the plane along the z axis and add the second location keyframe. Re-bake the simulation (time for another coffee). At the end of the simulation, delete the key1 shape and click on apply as shape key in the object modifiers tab. If you want to change something or add wrinkles in the curtain use sculpt mode.

Simulating the cloth

Simulating the cloth

Step 4: Window generator 2

First of all, enable add-on (file > user preferences > add-ons > window generator 2). It's very simple to use: click add > windows. The main options are: number of windows panel, type of top (flat, arc, triangle), thickness of frame, type of materials and, of course, size of each window. The add-on creates and assigns material to each part of the windows – it's a great help and we can save a lot of time.

Generating windows

Generating windows

Step 5: Modeling the room

Delete the plane under the curtain and start to model the room. Add walls, a top plane and floor. If you don't want to model all the objects of the scene, there are a lot of free models on the blendswap website (pillows, plants, furniture etc). Use some pictures on the walls and add just a little bit of imperfection to your scene, in this way it will be more realistic.

Modeling the room

Modeling the room

Step 6: Lighting setup

Change the render engine to cycles, add 2 emission planes inside the room; one in front of the curtain and the other to the side. Don't use pure white light – set the first one as warm light and the second as cold. Enable import image as a plane add-on and add a landscape picture outside of the window and set as emission (or use an HDR file as world surface).

The lighting setup

The lighting setup

Step 7: Texture and materials

Floor material: Download a wood texture and create a black and white copy. Change to 3D view in node editor window. Mix a diffuse and glossy shader and connect the wood texture to the color input of the diffuse material, then use the black and white version to determine which parts of the wood are glossy or matte (connect texture to the FACT node of the mix shader). The black and white texture could be used as a Bump map too.

Curtain material: Download a fabric texture (be sure it is seamless). Add a mix shader and mix the diffuse and velvet material. If you want to change the color of the curtain add a color mix node with the texture. If you want the curtain a bit translucent use a second mix node with a translucent shader and use the same fabric texture (black and white version, more contrasted) to drive fact input.

Pillow material: This is simply a velvet shader.

The material setups

The material setups

Step 8: Render setting and postproduction

Enable AO pass, set render samples at 2000 and hit F12 to start the render. At the end of the render process save the images (AO and Combined channel) and open them in Gimp. Use the AO channel to improve the image, add a bit of glare effect on the windows.

The final renders

Related links
Get your free copy of Blender!
Free blends here!
Filippo Veniero's website

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