Reflected Parallel Projections (the old question)

Could we please have reflected parallel views? Please please please? Lighting designers rely on these for placing lights.


Do you want a display mode?

I want a viewport property. Like, we have rotate already–I would like “flip,” too, preferably both horizontal and vertical. Reason: when lighting designers place lights, they look down through the imagined ceiling to the interior layout underneath. So when placing lights, or presenting a lighting layout, a view called a reflected ceiling plan that shows how the ceiling that matches up with the the furniture and partition layout beneath is used.


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Sorry, I must be dense today. What rotate are you referring to? Any sort of screenshot would help me understand what you are after.

An option for this dialog box. There is already “Rotation;” it would be really useful if there were also a “Flip” or “Mirror” option. I’ll send you two samples by private message, since I can’t republish them; one is from Frank Ching’s, Visual Dictionary of Architecture and the other is from the mighty IES handbook. People who can’t see those can view some samples at this Georgia State class notes site, as long as it is up.

I would love this as well. Bellow is an example of a plan and its matching reflected ceiling plan:

Note that at the section line, the plan and the reflected ceiling plan are exactly the same. The area labeled as 1. Double height exhibition space is still in the same place and does not mirror to the bottom in the reflected ceiling plan as it would set your view to Bottom.

What I feel would solve this is to allow negative numbers in View Scaling under Options -> View -> Display Modes -> [Mode] -> Other Settings. Currently you can enter a negative value, but it seems that anything <=0 is treated as 1. If this worked, you could get a mirror image, which would work for a reflected ceiling plan.


This would be hugely helpful for architects (and set designers).

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@pascal, @jeff, @John_Brock, @BrianJ

Do any of you guys understand this request with respect to how it would fit into Rhino? I’m stumped and don’t know what to file in our wishlist.

It’s like putting a mirror on the floor and looking into it to see the ceiling - essentially it would be a “mirrored” viewport transformation with the mirror plane being parallel to the XY plane.

I don’t know if that explains it better…


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Here is a visual description:

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I guess from a developer’s perspective it might be a horizontal section taken at ceiling level. I don’t know what this means in practice, perhaps it would be as simple as a relabeled floor plan.

Okay, so you guys just want the -1 horizontal scale in view scaling to flip the image. Is that correct?

All that’s being asked here is for the ability to “mirror” the view’s projection across one or both of the primary construction plane axes.

I believe Sam’s suggestion would work (or should theoretically) if -1.0 were allowed. However, I’m not sure what you’d get (or even expect) when anything but -1 is specified. Adding “Flip” and “Mirror” to the viewport dialog (as suggested) is also another possibility, and probably makes more sense from a usability point of view.

correct me if I’m wrong @Helvetosaur @cosmas @rfritz but I don’t think “flip” is being asked for. An object on the left side of the plan view should be on the left side of the RCP.

It’s as if you’re above the ceiling looking down through the ceiling as if it is glass. You’re absolutely right. The left side of the plan view would be on the left side of the RCP.

Hi Jeff,
I think it’s not a mirror or flip in the viewplane but rather a Z of -1.
The geometry mirrored over the viewplane.
Just like watching in a mirror and seeing yourself. Right is still right and up is still up.


For me, that’s a mirror in Z… --Mitch

If that’s true, then we’re not talking about the same thing… The reason I thought it was simply a projection flip was because of how Sam explained it and where he wanted to change the setting. If it’s just a transformation of the geometry, then that can probably easily be done with a simple plugin, although picking would most likely be messed up.

Sam? Anyone else?

It’s a flip of the bottom view of the ceiling, so that you see surfaces the bottom of the ceiling, but in the same orientation as the plan view of the space. This is important so that one can overlay the RCP on the plan, allowing one to easily visualize the relationship of light fixtures (and other devices, but I do lighting) mounted on the ceiling with the furniture and partitions of the plan below.

I was quite surprised when I realized I could not get this out of Rhino!

Mitch’s explanation of the reflected ceiling plan, that you are looking down at the ground which is a mirror so your see the ceiling, is the correct idea (or at least what I am after). The way I do this in Rhino currently is once I have my room (or whatever) all modeled up, I insert that into a brand new file as a linked block (so that when I change the model for the plan, the RCP will update). I then mirror that inserted block in the new file, and set my view to Bottom, and use the same clipping plane I used for the plan but flip its direction. The direction of the mirror (left for right, or top for bottom) depends on the bottom view’s camera up direction, the default in Rhino is to mirror top for bottom.

It would seem to me, but perhaps I am missing something, if I set up a display mode with the vertical scale = -1, I could set my detail to bottom, I would then have what I am after.

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