Question about perspective

Hi all,

Rookie Arch/Viz Question Please ... and I hope I can make this make sense. If you are creating a scene in which the view contains a room with a vertical wall corner, a subject (chair, etc...) and floor/wall line - is there a rule as to what to line up as a straight line? The vertical corner, floor line or subject? Seems like if I line up the vertical corner the other elements have a noticeable [unsettling] lean, this can happen with the lining up the floor line as well. I'm leaning toward getting a pleasing alignment with the subject - but the other elements form a subtle "v" if that makes sense. Maybe that is alright. Just wondering what the rule of thumb is concerning this issue.

Thanks!

Generally speaking you want all of your verticals to be vertical, but it of course depends on what the shot is and so on...

Some screenshots/images would really help.

Thank you for the reply Chris. Below is a quick scene to illustrate my question. The first image has the vertical corner lined up - looks good in that respect but the floor slant is distracting to me. The second shot has the floor lined up - really don't like that! And the third shot has the flat surfaces of the subject lined up - both corner and floor out. Maybe the presence of the grid is making this more obvious, but I applied the grid because something was nagging at me about the alignment.

Thanks!

Thanks, Chris! I posted some shots but I think a moderator must approve the post first. :/ Should pop in shortly I hope.

Well, in the mean time try having a read through this:

http://www.ronenbekerman.com/photographic-approach-in-architectural-visualisation/

Hope it is of some use to you.

This is useful too. Illustrates why we do it this way.

http://www.gsd.harvard.edu/gis/manual/graphic_style/jill_allen/3D%20Images%20-%2011-05-09.pdf

Also a good read:

http://digital-photography-school.com/divine-composition-with-fibonaccis-ratio-the-rule-of-thirds-on-steroids/

Great script:

http://www.scriptspot.com/3ds-max/scripts/imagecomphelper

Okay, great, thanks for the links and script!! Will be reading!

Hey, how do I flag a moderator down to see about getting the post in here? It's been a long time. Thanks!

Edit - something weird going on with my account, too!

Right, not sure what happened to the other post so I'll try again here.

1st pic - vertical corner lined up - looks good but floor is dipping below horizontal - the grid may be calling undue attention to that. Subject (chair) is slightly canted.

2nd pic - floor lined up - not pleasing to the eye.

3rd pic - subject lined up to the grid - subject looks good but walls and floor lines are unsettling to me.

From reading the links (thanks again!) the vertical is the best option here. I tend to agree - the grid is making the other lines stand out as "off"

Thanks for looking!

It looks like you're rotating the camera to line things up, rather than using what's known as Tilt/Shift, or perspective correction.

With VRay you have a "guess vert" button that will line the verticals up, but the standard max camera has no such equivalent, so you will have to do your perspective correction in photoshop, which is found under Filters/Lens Correction and then go to the "custom" tab, use the vertical perspective slider.

Without tilt/shift functionality, there is no way of doing this kind of correction in camera. It is the same in real photography too, Tilt Shift lenses are available but invariably very pricey (£900+) so most people resort to using photoshop, or similar. Don't rotate the camera, keep it completely upright; rotating it will only complicate matters further when you come to correcting it.

Ah, I see! I've heard of the Tilt Shift lenses for photography. I guess it makes sense they would apply in CG as well. So all interior scenes of this type, done in Max for example, have had to use the tilt/shift correction? Or does it make more sense to avoid the issue if possible?

Thanks!

Yeah, the majority will have had some form of correction, be it tilt shift or Photoshop.

That said, it isn't always favourable. It really does depend on the shot because the further away you get from "straight on", the more distorted it will look when applying lens correction.

A shot like this for example would be almost impossible, and pointless to correct the perspective on:

However the shots that you posted earlier would certainly benefit from vertical correction. I have yet to use horizontal correction in anything other than trying to photograph a completely flat elevation of a building where I've been stood a foot or so left or right of centre.

 

With VRay you have a "guess vert" button that will line the verticals up, but the standard max camera has no such equivalent, so you will have to do your perspective correction in photoshop, which is found under Filters/Lens Correction and then go to the "custom" tab, use the vertical perspective slider.

There is "camera modifier" in 3dsMax that lets you automatically correct verticals as well, it's been there always. But Vray additionally has shifting, so it's much more useful.

You learn something new every day!

I do not know why, so many people in archiviz, makes the vertical lines literally vertyical with no perspective distorsion at all?

By clicking "guess vertical" on Vray camera, or added 3dsmax camera modifier.

Perspective angles of 80-100grads, bring more life to archiviz images.

Just 2cc...

Like I said, it depends on the subject matter. You can use converging verticals of a skyscraper to really emphasize height, but for your day to day photographs I would argue that it looks far better to keep your verticals vertical. It's not just something borne of arch viz people, it's something actual photographers employ too.

When you take a picture of a house from close up, with a medium-wide angle lens the photograph will look wrong because of the converging verticals, even if it doesn't look wrong from where you're standing. This is because the brain automatically interprets what is vertical and what is not when you're out and about in the real world.

Another practical reason is Photoshop post work. If your client decides at the last minute he wants

a green tinge on 100 separate rectangular windows on a facade it's much easier to select them if vertical lines are vertical.

Same with placing post people and trees, etc.