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RViz Grid Direction

asked 2019-08-11 12:16:07 -0600

pitosalas gravatar image

I'm trying to make a little sense of the grid that is drawn in RViz relative to its frame. I set it to be tied to <fixed frame="">. I want to be able to look at the grid and understand where on the displayed grid, for example, I would find point 1,1.

It seems to me that vertical is x, with zero in the middle, and positive up. Makes sense. But then that horizontal is y. But from my coding it is acting as if left is positive and right is negative.

Is that true, or is there something in my setup that is incorrectly configured? THanks,

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answered 2019-08-11 17:23:34 -0600

As described in REP 103 the default convention is x forward, y left, z up. The grid display shows a grid in the xy plane, with the option for 3D visualization also using the z axis by setting "Normal Cell Count" to a non-zero value.

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Thanks but its still confusing me, despite the REP. We are talking about the projection of XY onto a screen which is placed vertically in front of my face. X being "forward" doesn't help much. If I lay it flat on the table (conceptually) then x = forward = "up" makes sense. And Z being "up" only makes sense again if we place the screen flat on the table.

So I guess the way I should think of it is that the screen is "looking down" onto the plane and hence Y is left. Ok.

pitosalas gravatar image pitosalas  ( 2019-08-11 18:25:11 -0600 )edit

I highly recommend adding the axes visualisation to RVIZ so you can see which axis is which: X = Red Y = Green Z = Blue

Ignore the computer screen completely since you can rotate your view (almost) any way you want, and just relate things back to the colored axes.

PeteBlackerThe3rd gravatar image PeteBlackerThe3rd  ( 2019-08-12 03:53:07 -0600 )edit

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Asked: 2019-08-11 12:16:07 -0600

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Last updated: Aug 11 '19