Y axis flipped in footprint editor

I see that the lower part of the screen is positive Y values and the upper port is negative Y values. Any reason why this counter convention?

I see that a lot of footprints are missing models and of course there are always going to be footprints to add. How do I get involved in helping create new footprints?

It is not counter convention. Only counter the convention you are used to :wink:

But you will be happy to hear that version 6 will add options for user control over the coordinate system which will include selecting the direction of the y axis.

Well it basicaly means that the convention is that I am looking from the bottom of the board. I am sorry but there is only one convention, +X goes right’ +Y goes up and +Z comes towards you, try telling the 3D CAD world that there is more than one convention, this becomes a big deal when I want to add 3D models as I have to position the model in 3D space to line up with the footprints coodinates. I now have to setup the model in 3D cad with inverted Y coordinates.

it can be worked around of course now that i know.

No you don’t. KiCad knows that step uses a different coordinate system and it works correctly.

OK, good job you just told me :slight_smile: so it just mirrors the Y coordinates? And no, Step does not use a different coordinate system, KicCad does. All 3D CAD programs have the same coordinate system. This way companies can exchange models all based around the same coordinate system and develop models seperately and then simply line the coordinates up when they bring different parts in from different sub contractors.
If the X axis was the oposite way around that would not be a problem because the space would simply be upside down so you just rotate around the Z axis, but it is not. If you rotate around the Xaxis you will get your models upsidedown or you say that the view in the footprint is from the bottom, otherwise the only way to fix it is to take the step and mirror it.

In all graphs electrical engineering or otherwise +Y goes up :grinning:

The other thing i have just found is that saving a wrl file from freecad has not produced a file that Kicad can read. I’ve used the original wurth step model instead.

use kicad stepup extension.

You might want to read this topic, it has some heated opinions

Some people are uncomfortable with Y axis being flipped, some don’t care, for others it’s actually the right way down. Either way it will be configurable soon.

And yes, do use the stepup plugin for freecad, you won’t have to manually align your models or muck around with wrl settings. Makes exporting models (and few other operations) as easy as it can be.


It will not happen in v5. And v6 is at least a year or two away. So i would not call it soon.

Patch for that is already in the middle of review, it will be in nightlies soon.

Even Freecad cannot reopen the exported model so i don’t know what happened.

Nightlies are not what i would count as “usable for production” (I know i know you are excited to tell everyone it will be available soon but please remember to add massive disclaimers about what nightlies are as most users are not used to such a concept.)

We even have a default disclaimer in the FAQ for this very reason: Is it a good idea to use a nightly build version?

Apparently lots of people never went to school :wink: This is not something i made up, every graph i have ever seey is done this way and when I joind a company that uses 3D CAD low and behold they do it the same as I was taught at school… Must be a conspiracy of some kind :wink:

2d Graphics programs (and some 2d graphics libraries) use top left as 0,0 and increase both axis from there. Meaning there is more than one convention (It even has a name. Left oriented coordinate system.)

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People who paid attention in school know that the direction of axis is completely arbitrary. Just because graphs are one way doesn’t mean CAD programs have to do the same. In computer graphics Y axis being downward is very common.


Quite, if KiCad is to gain mainstream acceptance it must be stable unless you want to suffer the fate of circuit studio, i am sure i am not the first to leave a ship that is sure to sink and i will be mightily pissed off if a prgram I am trying to use to make serious products I wish to sell misbehaves and ruins designs. I will stick with current stable releases and be grateful.

you can flip your 2D space if you wish but you cannot do that with a 3D space as you flip the Z axis as well. Find me a graph or diagram that uses a flipped Y axis.

You think of it wrong. If you flip the z axis above the kicad coordinate system then it is a normal right handed one. (looked from below) It is however a left handed coordinate system which means the z axis still points out of the screen. (The mathematics behind it do not care.)

Here the german wiki article that explains this well: https://de.wikipedia.org/wiki/Rechtssystem_(Mathematik) - or see the https://en.wikipedia.org/wiki/Cartesian_coordinate_system (section In three dimensions for the english version)

The only real problematic thing i see with kicads coordinate system is that rotation (of for example pads) uses counter clockwise as positive which would mean a right hand coordinate system is used for that part. (arcs however use clockwise as positive angle which would be correct in kicads left handed system.)

Yes i said above that basically you are looking from the bottom, that is the only way of reconciling it. i don’t know about the math, i thought is was just an established convention the same as we all agree what is left and right. The yanks use a different 2D drawing projection from us but that is less of an issue because the relevance is only in the drawing itself and does not need to be compatible with other things.

I think the arrival of 3D models and the conversion of the space from 2D to 3D is causing the problem.

Nope. You still misunderstand. A left hand system is not a right hand system looked from below. There is no way to rotate one to the other. They are fundamentally different but equally valid. (They are mirror images of each other. Mirroring is an operation that we humans can not intuitively do for 3d things as it is something that is impossible for a real thing.)

And yes it is the case that a right hand system is kind of the norm nowadays. But not back when kicad was first developed. This is why an abstraction layer will be added in future to give users a way to view coordinates as they like them.