Vanishing points in Render
When you press F12 and get your render, you see an image as seen through the camera's "perspective". Like how you can view your model in 3D View from the top, front, side, or user perspective, you can render your object from different perspectives. This perspective takes into account the lens size, type, and offset in giving you that picture. Each perspective uses a different number of vanishing points. If you look at a 3D image of a cube, you will see three kinds of edges: vertical, horizontal, and depth. If all of the vertical edges are exactly parallel, there is no vanishing point for them. If however, they are not parallel, if you extended them by continuing them with a ruler, they would at some point intersect. That point is called the vanishing point.
For special purposes, different kinds of render cameras can be set up to give you different perspectives. For reasons discussed below, you may wish to limit the number of vanishing points, especially for architectural purposes. Architects and drafting people are responsible for rendering the object or building with true dimensions and true relative proportions. If you look at that example render, the building looks all sorts of distorted, like it had been made of mud and was collapsing. If you told a builder to build that, you would end up with a building that actually had leaning walls and rooms that were narrower at the top. Way back in the old Greek days, when they started building tall columns, they built them thicker at the top than at the bottom, so that when viewed looking up, the two sides would look straight up and down. Then they even started narrowing the columns at the top to give the illusion that the building was taller and would look higher. During the Renaissance, the concept of using vanishing points in art evolved. Blender offers a few tricks of its own to let you do the same.
To follow sections below you will need to know how to adjust Camera_Settings
Three Point Rendering
This is reality, and there is nothing wrong with that. When you next step outside and look at a tall building, this is what you actually see. However, your mind knows that the building is square, and can adjust your perception of the building so that you are not scared that the building is going to fall over.
Two Point Rendering
To achieve 2-point rendering:
- Use a short wide angle lens camera, say with a Lens Size of 10 mm placed close to the building, or a long lens farther away from the building. These differences affect the depth of the building render, with longer lenses making the building appear thinner and less dramatic or distorted. The example uses a 40mm lens.
- Position the camera off to one side of the object, vertically halfway up the building to minimize distortion of the vertical building edges. You may alter this vertical (Z value) position to be slightly higher than ground level or higher than the top (if you want to see the top of the object or building). To show the front bottom corner of the building jutting out, raise up the camera.
- Angle the camera to be looking away from the building and directly level at the horizon - not pointed up or down (note the 20 degree Z angle in the example). This should make the vertical lines parallel. The more the camera looks at the object, the closer the vanishing point for the horizontal lines, and perceived depth will increase as that vanishing point gets closer as well.
- You may have to angle the camera slightly down (just 1 degree or so) so that vertical lines appear vertically up and down, both near and far. If the lines are curved, use a longer lens. With your 3D View set to Camera view, use the passpartout or pixels on your monitor to determine vertical.
- Move the camera toward/away from the object until it appears near a corner of the render and is the right size.
- Adjust the Shift: X and Y settings until your object is positioned properly.
One Point Rendering
To get 1-point (1pt) renders,
- To get more dramatic depth lines, use a short wide angle lens camera, say with a Lens Size of 10 mm, very close to the building. For a more normal appearance, stick with the 35mm lens.
- Position the camera off to one side of the object, slightly higher than the top (if you want to see the top of the object) or at ground level (the example image has the camera almost at ground level). If you position the camera below ground level, the bottom depth lines and horizontal lines will merge up (become congruent) for a very dramatic effect.
- Angle the camera looking straight back, perpendicular to the true face. Vertical lines should be parallel. Rotate the camera on the Z axis slightly toward the object until the horizontal edges are also parallel. Technically, you are correcting for parallax (just a casual line to drop on your girlfriend to impress her). The example has the camera rotated 0.5 degrees toward the object.
- Move the camera toward/away from the object until it appears at the proper size relative to your passpartout.
- Adjust the Shift: Y settings until the bottom of the passpartout (or title line if you want to show some approach ground in front of the building) is even with the bottom of the building. Adjust the X setting until the building is centered (or slightly offset from center for artistic appeal, or to show the parking lot next to it) as shown.
In the example screenshot, the Lens is 35, X is negative and Y is positive. The camera is off to the right of the object, even with the bottom of the building. If X & Y were zero, the building would have appeared off camera, in the upper left-hand corner of the passpartout.
|Parallel Horizontal Edges|
|You can use the lines of the passpartout as a guide in rotating the camera to determine when the horizontal edges are parallel.|
Zero Point (Orthographic) Rendering
To get an Orthographic render:
- Enable Orthographic in the Camera panel. This makes at least one face to be true to the camera.
- Point the camera at the object
- Position the camera or alter the Scale so the object is the desired size
With Orthographic cameras though, Lens size is irrelevant, since light rays do not converge to the camera from a field of view. They come in parallel, and so you can only Scale the camera size to take in more or less of that huge plane. Note that Shift X & Y are zero, and that the camera is positioned perfectly off at a 45 degree angle to the object/building, and is rotated exactly 45 degrees to face the building. Thus, the near edge is aligned with the back edge (since the object is square). Orthographic renders are usually made at 30, 45, or 60 degree angles to the object. Specific measurements are left to reader using triangle math.
Isometric Renderingcomplicated vector calculus in Wikipedia gives us a convenient shortcut. To get Isometric Renders:
- Make your camera Orthographic
- Add a "Track To" constraint (Object F7 context, Constraints panel) to the camera for it to Track To the object (type the name in the Target OB: field), using To: -Z and Up Y.
- Position your camera so that it is 45 degrees in the XY plane from your object, and raised at a 30 degree angle. If your object is at XYZ (0,0,0), then your camera should be at (10, -10, 10), or for a view from the left side, (-10, -10, 10)
- Adjust the Scale of the camera (Editing F9 context, Camera panel) so that the object fits within the passpartout
- Adjust the Shift: Y value so that the object is centered in the render.