Inverted UCS possible?

[CGriffin]

I am working with a vendor to simulate a transport conveyor system. I'm drawing each portion of our system in CAD so they can easily import XYZ data & other information easily.

The simulation software is a little strange in that +X goes to right but +Y goes page south (vs page north). The degrees of rotation are backwards, too... 0° is still right, but 90° is page south, 180° to the left & 270° is page north.

So far, I can handle all of that... but the Z elevations of different conveyors end up as negative numbers? When I redefine X & Y, Z naturally goes down/away from the viewer - if that makes sense?

My system is drawn 3-dimensionally in the default XYZ directions... but I'm wondering if there is a way to completely redefine the UCS so that Z goes in the other direction? I'm using data extraction to pull from the CAD model and use the Excel output to import into the other software... the only workaround I can think of is to just change the Z coordinates to a positive number, but my preference is to import the raw data without any manipulation.

When I've submitted data to them w/o changing the UCS, everything is imported backwards/mirrored... it's just weird.

[paullimapa]

You can save a changed ucs with a name

[leeminardi · Accepted solution]

All the CAD systems of which I know use the standard convention of a right handed coordinate system.   Point the finger of your right hand in the positive x direction and then sweep them 90 degrees to point int the direction of the positive y axis and your thumb will point in the direction of positive Z.  I doubt that the simulation software you are using does not adhere to the right handed coordinate system convention.

Your "+Z???" axis defines a left handed system which is not supported by AutoCAD.  You could define a UCS with X to the right, y down but Z would be point into the screen. 

[Kent1Cooper]

With positive X to the east and positive Z upward as in your image, you may not be able to have positive Y to the south, but you can still have the positive 90° angle go southward, with the ANGDIR System Variable setting.

[ChicagoLooper]

Hi @CGriffin

You need to evaluate the X-, Y-, and Z-axes and their relative position to one another.

Examine the three UCS below. All BLUEs are positive and all REDs are negative. Imagine X- and Y- axes are sitting flat on your Desktop while Z-axis is perpendicular to your desk and point up to the ceiling.

1. This is the 'default' UCS axes. The X and Y are co-planer while Z is pointing straight up toward the ceiling.
2. This is your Inverted UCS where the Z-axis is pointing to the floor. Positive-Y is pointing to your belly button. 
3. This the the Inverted UCS that's being rotated 180 degrees in direction of yellow arrows. When this rotation is completed, what happens? 

When the UCS in example 3 is rotated, it will end up like example 1, correct?

When you evaluate example 2, is it really inverted? When objects are defined 'relative to the axes,' are the objects upside down? Or are they right side up?   

Go to the store and buy some jacks. Or find some jacks in the supply closet.

Drop the ball and jacks simultaneously. Does the ball fall up to the ceiling and bounce back down and fall on your head?