Camera Series
Orthographic / Isometric Projection
Version 1.0, Updated Jun 2024 using Octane 2023.1.3 and Cinema 4D 2024.4
About This Guide
This is part of a series on using the Octane Camera. It was written using Cinema 4D, but the core concepts should hold in any incarnation of Octane.
This guide demystifies different parallel projections (including isometric) and explores the various ways of setting up C4D and the Octane Camera tag to get the more common ones for your renders.
It assumes that you’re already familiar with all of the basic settings of the Octane Camera and know how to change cameras and modes. This is all explained in (exhaustive) detail in the Octane Camera: Settings & Effects guide.
It’s also helpful to at least skim through Photography Concepts for 3D artists to learn more about photography as it relates to 3D.
PDF Version of this guide can be found here
Part I: Intro
Graphical projection is a technique for taking a 3D scene and displaying it on a 2D surface. The most common projection for physical camera gear is called “perspective”. Objects appear larger or smaller depending on proximity to the lens, and parallel lines appear to converge as they go back into space.
Most camera lenses are “rectilinear”, which means lines that are straight in the scene also appear straight in the image that’s captured. This is the same way our eyes see. This is also what both C4D’s camera, and Octane’s default Thin Lens or Universal Camera use.
All of the standard camera settings and behaviors are covered in the Octane Camera: Thin Lens & Universal Camera Types guide.
This guide covers Parallel projection, which is a family of projections that do not use perspective. Straight lines stay straight, parallel lines stay parallel as they go into the distance rather than converge, and objects do not appear to get larger or smaller depending on proximity to the camera.
Octane has an Orthographic projection mode in both the Thin Lens and Universal Camera types. Orthographic is a form of Parallel projection where the projection rays hit the 2D surface straight on (not at an angle like Oblique which is far less common).
As we’ll see, C4D also has a few modes for parallel projection, and some of them are compatible with Octane in various ways. C4D’s Parallel Camera can be used to mirror what we see in Octane’s Orthographic mode, and as of newer versions of Octane, C4D’s Isometric mode is also directly supported.
Lots more info about parallel projection can be found here.
Orthographic mode in Octane
First and foremost, we need to understand that in the C4D Camera/Octane Camera Tag relationship, data only travels one way. The Octane Object Tag can use some C4D camera data and even modifies one of the C4D fields, but the C4D Camera object is oblivious to anything happening in the Camera Tag.
This is important because when we’re framing our scene, we want to do as much in the C4D camera object as possible and let Octane pick those values up for the Live Viewer. If we were to nudge the frame over in the Octane Camera Tag for instance, the render would no longer match the viewport and it would make it difficult to predict what our final render will look like.
Like Octane, The C4D Camera object also has several camera modes, found in the Projection dropdown in the Object tab.
Important: As of this writing, Octane only directly supports C4D’s perspective and isometric camera modes. This means if we were to switch C4D’s projection to Parallel, Gentleman, Frog, Dimetric, etc, the viewport would reflect this, but the Octane render wouldn’t change and still be in perspective.
The good news is that Octane’s Orthographic mode lines up perfectly with C4D’s Parallel projection mode, so if we set both the C4D camera to Parallel AND switch to Orthographic mode in the Octane Camera tag, the viewport will match the render again and life will be good.
For the Thin Lens camera type, this is just a checkbox called Orthographic in the Thinlens tab. For the Universal type camera, this is a mode in the Camera mode dropdown called “Orthographic”.
The Universal type camera gives us a few more depth of field and lens effect options than the Thin Lens camera does, but otherwise it’s the same experience using either camera type.
Framing & Navigating with the Parallel/Orthographic Camera
Framing and navigating is a lot different with a parallel/orthographic camera than it is with a perspective one, so it’s worth taking a few pages to look at why that is and the best way to deal with it.
Important: Again, and this can’t be stressed enough: There is no concept of “the distance” using Parallel/Orthographic projection. Everything appears flattened and infinitely thin relative to the camera. It does not matter how close or far the camera gets to an object, the apparent size of it does not change.
Let’s set up some terminology to help make this easier. Different types of movement or rotation along different axes have unique names. Most of the time this is pedantic unless we’re on set, but it’s helpful when explaining what we can or can’t do with parallel projection. Pan, Tilt, and Roll are about rotating the camera, and Truck, Pedestal, and Dolly are about moving (translating) the camera.
Making objects in the frame larger or smaller
Dolly does not affect the size of the objects, so we need a different way to do that.
When we change the C4D camera projection to Parallel, we get a Zoom option. This is similar to digital zoom on a physical camera where it just crops in on a smaller area of the high megapixel sensor (not optical zoom, which changes the focal length and therefore affects perspective and background compression). Octane respects C4D’s zoom setting, so the render still matches the viewport when we change this.
Zoom is a multiplier, so 1 is “actual size”, 2 is 200%, 0.5 is 50%, etc.
Important: Octane does not support a zoom level lower than 0.17
Moving objects left, right, up, or down relative to the camera
We can truck or pedestal the parallel camera to make the whole scene shift horizontally or vertically on the viewing plane. We don’t have to worry about perspective problems, so it’s just a nice simple shift in view, which is great for both framing and animating. Typically we want to do this with the move widget instead of numerically because it affects P.X, P.Y, and/or P.Z depending on the angle we pick.
We can also use the Film Offset controls to shove the scene left/right/up/down relative to our view, and Octane supports that just fine.
Important: Octane has its own version of Film Offset called Lens Shift. This is located in the Thinlens or Universal tab of the Octane Camera Tag. In Cinema 4D, we want to avoid using this, because it doesn’t mirror what’s happening in the C4D viewport. It’s really only needed for compatibility with other DCCs.
Setting the viewing angle
This is kind of weird because of the whole lack of depth thing. With a perspective camera, we usually use Alt + the mouse buttons, or hold 1,2, or 3 and move around to frame our objects in the viewport. It’s intuitive and easier than setting numerical values.
Important: This only sort of works with the parallel camera - we can orbit the camera around to change our viewing angle and that also nudges the scene horizontally and vertically, but C4D pulls some shenanigans here where Alt-middle mouse (or holding 2) now changes the zoom instead of dollying the camera back. This really starts to cause problems thanks to a concept called clipping.
Clipping occurs when an object intersects the “lens” of the camera. We may be familiar with this from video games if the collisions aren’t set right and we can sort of look through a wall or inside an object by getting too close to it. No amount of viewport nav will solve this because zoom - and therefore Alt-MMB/holding 2 - doesn’t move the camera in 3D space in Parallel mode.
Important: In Cinema 4D, we can actually turn off clipping to avoid this. Octane doesn’t respect this setting though, so the camera ALWAYS has to be far enough away to avoid this issue.
If we’re not after a depth of field effect, the solve for this is just to keep an eye on the camera placement in the other viewports while navigating around and make sure we’re not intersecting anything. If we see objects start to clip, we can select the camera object, grab the blue handle (local z axis), and dolly the camera back until it’s not intersecting/clipping anymore. The good news is that as long as we don’t turn off clipping, we can see the issue in the viewport prior to rendering and correct it.
Focus and Depth of Field
Quirky behavior: As of this writing, it’s possible - but not easy - to get a depth of field effect using the C4D Parallel mode/Octane Orthographic mode combination. That’s because Focal Depth/Focus Distance changes the apparent size of the objects in Octane’s Live Viewer (but not in C4D’s viewport).
This makes focusing extremely difficult since the framing changes as the focus changes. We need to try to jockey the C4D zoom control to “back up” as we make the focus distance shorter (which is needed for a stronger DoF effect), and regardless of what we do, it will never match the C4D viewport unless the focus distance is 2000 cm. To make matters worse, Octane does not support a zoom level of below 0.17, so if our scene is pretty big, it’s very difficult to get everything into frame. Fortunately, we have one more option, but it’s restricted to one camera angle.
Isometric Camera Mode
Up until now, we’ve steered away from the term “isometric” because we already had two different projection terms we were using (Parallel for C4D and Orthographic for Octane). Isometric projection is a form of Orthographic projection where the camera is set at a particular angle so that a dimension of equal distance on all three axes measures the same in the render if we were to take a ruler to it.
In order to get measurements along the X/Y/Z axes to measure exactly the same, the camera has to be set to H:45°, P:-35.264°, B:0°. We can actually do this using the Parallel camera by setting those particular rotation values, but we still run into the depth of field problem.
Cinema 4D has an Isometric camera mode which locks the camera’s rotation values at the proper angle. Newer versions of Octane support this mode, which is great, and it has the added bonus of the Focal Depth not messing with the zoom in this mode, so we can do depth of field effects a lot easier - yay!
To set this up, we need to change the C4D camera’s Projection to Isometric. If we’re using a Thin Lens type camera, it just works out of the box - turning on and off Orthographic mode doesn’t make a difference. If we’re using a Universal type camera, we still need to set it to Orthographic mode.
Seems too easy. Is there a catch? Of course there’s a catch! The scene setup is really weird for this.
Object Positioning
First off, C4D’s Isometric camera mode has the Z-axis reversed from what we’re used to. Typically with any other camera, we’d position our objects facing “down” as seen from the top view so the Z axis is pointing back behind them into the distance. With the Isometric camera mode, this is flipped - we want our objects facing “up” in the top view.
Normally this wouldn’t be an issue because we could just orbit around the scene, but the Isometric camera rotation values are locked - no orbiting for us in iso mode! We need to set up our objects so they’re facing +Z (“left”), +X (“right”) or +Y (“up”). If we want to rotate the whole scene, we need to put it in a null that acts as a turntable and literally rotate the whole scene rather than orbit around it with the cam.
Camera Positioning
The coordinates of this camera mode are pretty bizarre too. Again, the camera rotation is locked. We can still navigate around in the scene using Alt-LMB/MMB/RMB or 1,2,3, but that only causes the camera to truck or pedestal, and then also affects the zoom level like the Parallel camera when we try to dolly.
We can no longer Pan, Tilt, or Roll. In fact, we can set the camera’s rotation values to whatever we want and the little camera icon in the 4-view will spin around all day, but it won’t ever affect what we’re seeing. It’s always. The. Same. Angle.
We can imagine a diagonal line that starts at world zero (X/Y/Z = 0) and goes out in either direction where the X, Y, and Z coordinates always equal each other. If we put the camera anywhere on this line (P.X=0, P.Y=0, P.Z=0, or P.X=10,000, P.Y=10,000, P.Z=10,000, or P.X=-238.4, P.Y=-238.4, P.Z=-238.4… the value itself doesn’t matter) the scene will always be frame the same in the C4D viewport with world zero being the center of the render.
Important: While C4D doesn’t care about the position of the camera relative to the objects, and won’t show clipping like Parallel mode does, Octane DOES care quite a bit about it. The camera needs to be in front of the objects (which in this case means positive values in P.X, P.Y, and P.Z), and it can’t intersect any of the objects, regardless of the rosy picture the C4D viewport paints for us.
Aside from all that, it works about the same as the Parallel camera - we can truck and pedestal and/or Film Offset to move the scene up/down/left/right, and we can use zoom to make things bigger or smaller.
The one big advantage we have in iso mode over parallel is depth of field effects, since the Focal Distance is not tied to the zoom like it is in the parallel camera.
Depth of Field in Isometric mode
Depth of Field covered in a lot more detail in the Photography Concepts for 3D Artists guide, and then the Octane Camera: Settings & Effects guide goes into how this translates to Octane.
Focal length plays a big part in the apparent DoF effect in a perspective camera. We’re looking at an Isometric Camera that has an infinite focal length, so that’s not relevant here, and we can ignore that.
Quick recap of how Octane and C4D handles focus and DoF:
The Aperture setting needs to be anything other than 0 in the Thinlens/Universal tab of the Octane Camera Tag to see DoF. The F-stop slider and Aperture sliders are linked. F-stop defaults to 2.8, but isn’t really because Aperture is 0 - move either slider to enable depth of field. The lower the F-stop value, the larger the aperture becomes and the more out of focus stuff appears in the render.
The C4D Camera object has a Focus Distance field in the Object tag. This defines the focal plane - everything on the focal plane is tack sharp, and then there’s a range in front of and behind it where things are acceptably in focus (this is known as the depth of field). Everything further than that range starts to go out of focus. We don’t directly use C4D’s Focus Distance because...
Octane has an Auto Focus checkbox in the Thinlens/Universal tab which defaults to ON and overrides the C4D Focus Distance Field. Auto focus focuses on the first object to hit the camera in the center of the frame. That’s going to be a liability here, so we should always uncheck it if doing Orthographic mode. When we turn it off, we get…
Octane’s Focal depth field in the Thinlens/Universal tab. This not only overrides C4D’s Focus Distance, but forces that field to match its own Focal depth. This can be set numerically or by using Octane’s Focus Picker (F-in-a-map-pin icon in the Live Viewer).
C4D still has one trick up its sleeve in the battle for focus: The Focus Object field. If we drop in a null or another object into that field, that becomes the focus distance and overrides all previous methods of focus. This is extremely useful for Isometric scenes.
What this means for us
Generally, the best strategy for DoF in Isometric mode is to put the camera as close as we can to the scene without clipping, and then create a null to use as the C4D camera’s Focus Object and place it on whatever we want in focus.
Then we need to turn on DoF by changing either the Aperture or F-stop field, and adjust one or the other until we have as much in focus as we want. If everything is too out of focus no matter how much we alter the Aperture/F-stop, we can start dollying the camera away from the scene - being sure to keep the same value in X, Y, and Z - and more will come into focus.
Again, objects in the scene will not change size as we can see in the illustration above. Dollying the camera only affects depth of field, not framing.
Wrap Up
If you made it through this guide, you probably have a much better understanding of how to work with a parallel/orthographic/isometric setup than you did before, and you’re aware of all the gotchas and idiosyncrasies involved.