3d camera up direction

[Jo-Jo]

I've been using the 3d picture control for about a year now, and I have become pretty good with most of the functions, but one thing still baffles me.  On the setup camera method I can't figure out what the up direction is.  The help file says "Sets the x, y, and z coordinates that define the axis that the top of the camera faces."  I thought this meant that it was a (unit) vector that pointed out of the top of the camera, but this isn't the case, it only seems that way sometimes.  Does anyone know how to use this thing?  I have a program that requires moving the camera around, and in some locations, and depending on what the camera is tageting, the camera inverts itself, or turns sideways.  I am certain that what I am using for the up direction is a unit vector that points in a direction 90 degrees from the target, which sometimes points in the direction the top of the camera is facing, and sometimes not.

~Benjamin

[falkpl]

I havent used the 3d picture tool too much but my guess is that the XYZ is a point that defined a vector from the camera to this point and this vector is the up for the camera.  A unit vector would make more sense though.  If this is right then it will work  the same as a unit up vector when the camera is at 0,0,0 origin of the model space.

[Jo-Jo]

No, this isn't the case.  I already tried that, it seems intuitively that that is the correct answer, but I'm now certain that is not how it works.

[falkpl]

This was just a guess.  I havent used opengl in a few years and have limited use of the labview 3d picture tool.  I have been trying to integrate it into some of my projects but hav not found a good fit yet.

Paul

[Donovan_B]

Hi Benjamin,

I have noticed the same thing on occasion.  Generally, it does seem that the up direction property is a unit vector from the top of the camera to the point specified in the space.  I was playing with this today and found that, sometimes, the image did invert.  I am not sure why this is happening yet, but let me work with this some more and I will let you know what I find out.

[Jo-Jo]

I figured it out.  See my explaination on the LAVA forum here:

http://forums.lavag.org/Setup-3D-Camera-Method-t9684.html&gopid=39479#entry39479

~Benjamin

[nrobles]

original link seems broken

new link : https://lavag.org/topic/6667-setup-3d-camera-method/?tab=comments#comment-39024

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@Jo-Jo  ha escrito:
I figured it out.  See my explaination on the LAVA forum here:

http://forums.lavag.org/Setup-3D-Camera-Method-t9684.html&gopid=39479#entry39479

~Benjamin

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