Making architectural line drawings with Blender
Scale model
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Making architectural line drawings with Blender

Line drawing with blender
3D-model by Saana Tammisto

Blender is able to produce quite nice line drawings, like seen in above. This is a short explanation of how this can be done.

First you need a house :)

Select on any mesh from house and remove its material.
Add a new material to the mesh and give it a name.
Set the color of the material to pure white and set Shadeless option on.

Let's copy that material to all other meshes as well.

Select all meshes (Select -> Select All by Type -> Mesh)
Select Object -> Make Links -> Material.

Now every mesh in your screen should be white. Make a test render. If you have multiple material indexes in same mesh, you have to remove them.

Some more settings:

Change background to white. This setting can be found on Shading panel (F5) under World button.
Set Edge rendering on from rendering setting. and set the Eint-value from Edge Settings large enough (over 30).
Disable antialiasing (OSA-button).

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Setting camera

In order to produce line drawing without perspective distortion, we have to use Ortographic camera. WIth Ortographic setting on,the distance of the camera does not affect the size of objects in the camera view.

Change your 3D-view to front (View -> Front) and align camera to view (View -> Align View -> Align Active Camera to View).
Select your camera, go to the Editing panel (F9) and set Ortographic button on.
Change 3D-view to camera (View -> Camera).
Adjust Scale setting so that your whole building fits to the view.

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Setting line width

The eint-value is NOT the line width setting, it is the line intensity setting. By eint-setting you can define how much details are shown inside outer edges.

eint = 40

eint = 0

As you see, the outer edges has same width no matter what the eint-value is. If you want to have thinner lines, you can render in higher resolution and then scale it down with Gimp. (The line rendering at the start of this page was rendered at 3500 * 2500 resolution.)

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Calculating the scale

Usually line drawings are made in scale. This requires some calculations to accomplish.

For architectural modelling with metric system it is natural to say that 1 Blender unit = 1 meter. So that default box in blender is 2m x 2m x 2m. If the Ortographic Scale setting is 2 and you render with 800x800 resolution, then 2 meters = 800 pixels. Well, that doesn't really mean anything since all that matters is how much that 2 meters is when it gets printed on paper.

When you render from Blender, the default DPI of that picture is 72. It means that the size of the image that has resolution of 800x800 is ~ 6,7 x 6,7 centimeters when printed. So, in that case 2 meters is 6,7 centimeters in paper which gives scale ratio ~1:30 (200/6,7 = ~30).

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scale ratio 1:50 with 300DPI?

What if we need a drawing in scale ratio 1:50 and we want to print with 300 DPI?

We must first set the Ortographic Scale setting because that's how we fit the building in the camera view. Let's assume that Scale is 24 and in centimeters that is 2400. By simple equation we can find out how large the printed version of image should be.

2400/x = 1/50 | :2400

x = 48

This gives 48 centimeters which means that 24 meters in real world would be 48 centimeters in paper.In which resolution we must render so we could print it at 300 DPI and have that scale ratio? From previous calculation we know that the size of the printed picture should be 48 centimeters.Because DPI unit uses inches let's change that 48 centimeter to inches. It is ~ 18,9 inches.

X/300 = 48/2,56 | x 300

x = ~ 5700

And that gives us the final resolution which is 18,9 x 300 = 5700 pixels.

Note: If you want to adjust the line size, you can render larget/smaller resolutions and then change resolution afterwards with image manipulation program.

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