Instant Perspective distortion
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Hello. For quite a while now, I've encountered some phenomena in Sketchup, that at first I wasn't aware that a change had taken place during a drawing session, but now, I realize, during a current drawing session, something had really taken place causes a RADICAL change in the way that the PERSPECTIVE of objects is displayed on the screen. This change appears to have occurred right after I added a "transparency" command to a material color. Although, that may or may not be the cause. Take a look at these two jpgs. One was exported ten minutes before the change occured, and the next was exported within minutes of discovering this change. I closed the program for the night, and rebooted this morning and opened the file, hoping that maybe something in my hardware had caused this...like an overheaded graphics card or something. But..it was STILL distorted or what I consider RADICAL perspective. Any insight would be appreciated, as this is not acceptable for presentation to viewers whom I share my drawings with. They look just awful.
Here is the one prior to change:
and here is the one AFTER the change..gak! just awful perspective
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Here is another one. I've searched all the Sketchup commands and I don't see anything that will alter this perspective "glitch".
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OMG!! never mind. 
I just found the answer. although I still don't understand something. There is a "zoom" feature button on the button bar which I believe is for "zooming" IN and OUT". And it DOES just that. However, under CAMERA, there is an IDENTICAL button called..."field of view", which when activated, does indeed "zoom" IN and OUT"...but ALSO zooms in and out in an ODD way, and affects the "perspective". I can't exactly define what this does, but it sure makes the perspective look wierd. Can someone tell me exactly what this tool does...at least in regards to "perspictive"? Thanks
fitZ -
http://en.wikipedia.org/wiki/Field_of_view
Im not entirely sure what it is myself, but basically it controls how much you can see either side of the camera. It's often increased when doing interior shots for this reason, as it means you can see more of the room.
Wit regards to the shortcut, i think your referring to holding down shift while using the zoom tool. You can change it back to 'normal' by selecting the zoom tool, typing in 35 and pressing enter.
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"Field of View" can best be explained with a camera metaphor. Think of the "zoom ratio" of your camera lens. If you have a wide angle lens, your field of view is "wide." ie. a large angle of view. (90 degrees, for instance) A "fisheye" lens has an angle of view of over 180 degrees.
Conversely, a telephoto has a very narrow angle of view. (10-20 degrees)
But here's the key: You can still obtain the same picture area with either a wide angle or telephoto lens, but the two images will look VERY different. Why? Because you will be very close to the subject with the wide angle lens and much farther away with the telephoto. So with a wide angle, close objects in the image are much closer and therefore larger, while faraway objects are much smaller. This leads to the syndrome of a person with a distorted big nose, when taken with a wide angle lens.
Conversely, when you're far away from the subject with a telephoto, all the elements of the image are pretty much the same distance away, so everything "looks" like their actual size. That's why pro photographers use medium telephotos to take portraits. It makes for a more pleasing rendition of the subject.
Now, back to Sketchup. The first "zoom" button you mentioned is more like moving closer or farther away from the subject, while the second "zoom" is like switching from a wide angle to a telephoto lens.
Does that explain it for you?
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Yes, it may look weird and even frightening (especially at this extreme wide angle) but it can be very useful sometimes (like in interiors as was mentioned above). It is also easy to do it accidentally since not only the FOV button can do it but the Zoom button as well if you (accidentally) keep Shift pressed down.
You can experiment with it however; choose the FOV tool and change the FOV to see the values also change in the VCB/Measurements. When there is no unit for it, it always means degrees and refers to the wideness/narrowness of the camera lens.
If you are familiar with photography,you can even type in the focal length in millimetres (I think this is calculated in mm's in the USA, too)
Bigger FOV values (degrees) mean shorter focal length and vice versa.
As a side note: good to know that scenes can "remember" FOV/FL values so you can even "play" little animations this way.
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@gaieus said:
(I think this is calculated in mm's in the USA, too)
well yeah, we don't have any lens manufacturers here
some specialty things and that's allall my gear is german or japanese but my film is u.s.a(kodak).. their film is measured in mm as well.. so are skateboard wheels.
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Like our water and gas pipes are still measured/manufactured in (fractions of) inches.
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@unknownuser said:
@gaieus said:
(I think this is calculated in mm's in the USA, too)
well yeah, we don't have any lens manufacturers here
some specialty things and that's allall my gear is german or japanese but my film is u.s.a(kodak).. their film is measured in mm as well.. so are skateboard wheels.
On old Leicas I have seen the focal length in cm too.
Film formats are a total mess: 5 x 4 means inches, 6 x 6 means cm etc...Anssi
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