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scaling
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March 01, 2010, 02:18:32 PM
All:

I made a Rubik’s Cube puzzle model approximating its actual size, then making another next to it but scaling it 10 X larger the original size being like a large carton or desk in size. Next to those adding a third 10 X larger yet like a garage about 21 feet cubed. Using TurboCAD’s Pro 15.2

Each of the three cubes now need a different setting for vanishing points to look about right.  The smallest gets a 6, the intermediate gets 12, and the large cube deserves about a 22 setting. 

I’m trying to derive a formula taking into account the distance from the objects corner to corner, the distance to the eye, and the altitude relative to the subjects.

Question:  Does the scaling factor change all objects on the drawing?  I tried to isolate the shapes as per their respective sizes, I thought.

Please advise,

Thanks,

Bob

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March 01, 2010, 02:55:38 PM
#1
"Vanishing point" generally refers to Perspective Viewing.  Is this what you are doing?

If so, are you having a problem finding one setting that makes all the components look correct in a perspective view?

Jeff

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* March 01, 2010, 02:58:19 PM
#2
All:

I made a Rubik’s Cube puzzle model approximating its actual size, then making another next to it but scaling it 10 X larger the original size being like a large carton or desk in size. Next to those adding a third 10 X larger yet like a garage about 21 feet cubed. Using TurboCAD’s Pro 15.2

Each of the three cubes now need a different setting for vanishing points to look about right.  The smallest gets a 6, the intermediate gets 12, and the large cube deserves about a 22 setting. 

I’m trying to derive a formula taking into account the distance from the objects corner to corner, the distance to the eye, and the altitude relative to the subjects.

Question:  Does the scaling factor change all objects on the drawing?  I tried to isolate the shapes as per their respective sizes, I thought.

Please advise,

Thanks,

Bob


Any View Angle you set should apply equally for all objects in the drawing. In the attached screenshot you see three boxes, each 100000 inches deep and differing only by their width and height dimensions. Smallest is 1×1; next is 10×10; largest is 100×100. I experimented with various View Angles, and in all cases the Vanishing Point appeared the same for all three objects.

Henry H

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March 01, 2010, 04:19:44 PM
#3
All:

I guess the larger the cube (relative to the original Rubik’s cube), the further beyond that structure has to be from the eye (or its neighboring cube) to arrive at the same vanishing point value given on the sliding bar - 6 in this example, the same for all three structures.

Things get more and more complex the more and more you delve into things.  But thanks for reading and explaining the interpretation,

Bob
« Last Edit: March 01, 2010, 04:25:13 PM by Bob »

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* March 01, 2010, 08:04:15 PM
#4
I guess the larger the cube (relative to the original Rubik’s cube), the further beyond that structure has to be from the eye (or its neighboring cube) to arrive at the same vanishing point value given on the sliding bar - 6 in this example, the same for all three structures.

Hm? What sliding bar, Bob?

Henry H

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March 02, 2010, 04:33:59 AM
#5
All:

The light bulb effect I guess, if you employ more than just one vanishing point – at first I was thinking you had to.  The model then takes on an appearance of a “collage” or a montage quality, forfeiting that expected “unified” look of a single vantage point has over the entire drawing.

Perhaps that’s why TurboCAD blankets the entire drawing in only one vantage value.  Maybe the term "sliding bar" is not used in TC, I was talking about the adjustment device used in changing Vanishing Point values.

However, is there some rational for the values given in the software?  I mean 5.7 for vary little taper on up the scale.  Knowing the reason usually helps remembering the thing.   

Thanks,

Bob

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* March 02, 2010, 09:38:15 AM
#6
All:

The light bulb effect I guess, if you employ more than just one vanishing point – at first I was thinking you had to.  The model then takes on an appearance of a “collage” or a montage quality, forfeiting that expected “unified” look of a single vantage point has over the entire drawing.

Perhaps that’s why TurboCAD blankets the entire drawing in only one vantage value.  Maybe the term "sliding bar" is not used in TC, I was talking about the adjustment device used in changing Vanishing Point values.

However, is there some rational for the values given in the software?  I mean 5.7 for vary little taper on up the scale.  Knowing the reason usually helps remembering the thing.   

Thanks,

Bob


Now I'm more confused than ever, Bob. I understand what a Vanishing Point is, but TurboCAD seems not to use the concept or even to recognize the term. (A search for "vanishing point" in the Help file turns up empty.)

In any case, each set of parallel lines in a drawing has its own unique vanishing point, so in general there is not just one VP in a drawing. In the attached screenshot, for example, all the vertical edges of the three objects are indeed parallel and therefore will meet in a single VP if extended. The horizontal edges, however, comprise several different sets of parallel lines, each of which has its own Vanishing Point.

Henry H

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March 03, 2010, 06:30:20 AM
#7
Henry:

I can"t send a TC file just now, as my "primary machine" is in the shop - an issue with the sound card as I was told, not to be trite but they say a picture is worth a thousand words.

I was imagining the typical view of a RR track going off in the distance becoming one point - for that axis.  As you said   "each set of parallel lines in a drawing has its own unique vanishing point, so in general there is not just one VP in a drawing" 

On your drawing given if you carry out the lines toward the horizon. shall they not converge?  Surely the same holds true for the other two axis, is that what was meant by the word "set"?

Bob, (the dead horse beater)

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* March 03, 2010, 08:21:54 AM
#8
Henry:

I can"t send a TC file just now, as my "primary machine" is in the shop - an issue with the sound card as I was told, not to be trite but they say a picture is worth a thousand words.

I was imagining the typical view of a RR track going off in the distance becoming one point - for that axis.  As you said   "each set of parallel lines in a drawing has its own unique vanishing point, so in general there is not just one VP in a drawing" 

On your drawing given if you carry out the lines toward the horizon. shall they not converge?  Surely the same holds true for the other two axis, is that what was meant by the word "set"?

Bob, (the dead horse beater)

Yup.

Henry H

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