SceneTransforms.wgs84ToWindowCoordinates incorrect when tracking entity

[hpinkos]

Reported in the forum
https://groups.google.com/forum/#!topic/cesium-dev/XYAGd93UkmA

He included a really good example in the post.
SceneTransforms.wgs84ToWindowCoordinates returns the wrong window coordinates when the tracked entity has a different position from the one being converted to a window coordinate.

[jpremkumar]

Has there been any progress on this issue?

I would love to incorporate into my project.

[mailmrmanoj]

Hello All,Pls have a look at this issue..
Thanks

[vijquick]

+1
Any update on this issue please?
Thanks

[gantamk]

+1

[batakpout]

+1

[svsachin13]

+1
can anyone take a look at this please?

[sagariEduri22]

I'm also facing the similar issue in my project.please update the progress on this issue.

[devidatta45]

+1
can anyone please help me on this..

[kankarsuresh]

+1
Thanks jpremkumar for such a good example

[swapna-devadict]

+1
facing the same issue, can anyone help on this please..
Thanks

[hpinkos]

@bagnell can you give @jpremkumar advice for fixing this issue?

[jpremkumar]

Hi @bagnell,

Based on the discussion I'd with @hpinkos, it looks like the problem could be related to "camera transformation".

Can you advice on how to proceed further?

[jpremkumar]

Any progress on this issue or anyone advice for fixing this issue please.

[mramato]

While I can't say exactly what the problem is, it's going to be related to the camera viewMatrix and transform properties. When tracking an object, the transform is something other than the identity, which means that at some point during the calculation, we probably need to transform the position to the proper reference frame.

I would recommend you see if this works in 2D when tracking and object, if it does, then most likely you need an else block after the if block on line 117 of SceneTransforms.js that handles 3D and CV and applies the camera transform to the input data.

If it doesn't work in 2D either, then you might need to always apply the transform.

There's a chance the problem is something else entirely, but that would be the best place to start. Sorry I can't be more specific (or else I would have fixed it myself already), you'll have to dig into the code and experiment.

Thanks.

[jpremkumar]

Thank you @mramato for the guidance. Let me experiment...

[jpremkumar]

I've spend good time with #3247. It looks like, tracking is not working in 2D mode as well. I've tried with different transformation on worldToClip (line no 68) and clipToGLWindowCoordinates (271) functions, but no luck :(

White text "Sample Popup" is the billboard.

branch: models-2D - Output

[emackey]

@jpremkumar forgive me if you already know this: HTML measures vertical coordinates starting at the top, increasing as you go down, like text. WebGL, like many graphics systems, places the origin in the lower-left, with vertical coordinates increasing as you go up the screen. From your screen cap, it looks like you just need to flip your Y coordinate. (Also beware that the canvas may be a different vertical resolution from CSS pixels in the DOM).

[jpremkumar]

@emackey, You are right, I've flipped the position of clip coordinates, before it convert to windows coordinates.

Source: SourceTransforms.js Line#191

positionCC.y = -(positionCC.y);

The changes addressed the positioning but am not sure about the impact. Could someone assist in validating the fix?

[emackey]

@jpremkumar So it turns out we have a bug where the Y coordinate got flipped, written up as #3920. It's very likely the fix for #3920 will involve flipping it back the way it was.

[jpremkumar]

Thank you @emackey for the update.

[jpremkumar]

Hi @emackey, I've tested the bug #3247 with the latest Cesium version r1.22. Still facing the same positioning issue. The #3920 is not the fix for #3247. When I flip the Y coordinates in the SourceTransforms.js, then it works.

Source: SceneTransforms.js Line#191

positionCC.y = -(positionCC.y);

Can you assist on this please.

[eric-g-97477]

If it helps, I've updated the original sandcastle code from the forum. It was no longer working.

working sandcastle