Model aggregating in viewer - coordinate issue

问题

I am dynamically aggregating models in the Viewer (coming from multiple BIM files). Basically, I initialize the viewer, and then LoadDocument and LoadModel for each model that user chooses to view, dynamically.

These are mostly NVC files (what I used for testing), which are sharing the coordinate system. Models getting dynamically loaded and getting 'stitched' correctly.

However, coordinate system is getting screwed up when the second model gets loaded - not always but in some cases (in v6.3 - haven't checked previous versions). When this happens, I can notice the followings:

1. When I click 'home' icon in the viewer, it doesn't show the full aggregated model but only shows the first loaded model in the center and rest go outside screen.
2. When I click an element to select, it selects something else (with an offset), and some cases selects nothing (meaning, clicked coordinates has been interpreted incorrectly).

I have tried multiple combinations and this problem seems to happen when first loaded model is not occupying full size of the aggregated model (say, one floor of the building).

I figured out a solution though. After loading the models (every time when user choose some), if I 'hide' all models and 'show' them again, it fixes the problems with click and AGGREGATED_SELECTION event.

This is not a nice user experience because I want to be able to load the models in the background while user is moving around the previously aggregated model-set. If I hide/show after loading the new one, it will be annoying to user.

Is there a way to 'reset' the coordinate system of the viewer (to the same effect what happens when hide/show the models)?

I would appreciate some help to get around this issue.

Thanks Bandu

回答1:

ok, so there is a massive offset, causing a precision issue. Which is why you are seeing lots of 'jittering' of the camera.

To fix this... we need to correct the massive offset, by returning all the geometry closer to origin manually. (or fixing the original navisworks file).

First, let's roughly figure out the offset value...

Alt-Click anywhere on an object to create a pivot point and get the x,y,z value using this trick (https://github.com/wallabyway/markupExt/issues/2).

You should see an xyz value like this... Z.Vector3 {x: 1296285.515098644, y: 14995636.431742325, z: 364.26238179027337}

Now, adjust set the global offset using this value, to correctly move all the models closer to 0,0,0. like this...

line 70:

var modelOptions = {
    sharedPropertyDbPath: doc.getPropertyDbPath(),
    globalOffset: {x:1296285.515098644, y: 14995636.431742325, z:0}
};
viewer.loadModel(svfUrl, modelOptions, onLoadModelSuccess);

`

This reverses the effect of this big offset. The result is the geometry stops flickering and the camera movement stops 'jittering' due to precision issues.

Let me know if that works for you. Michael

来源：https://stackoverflow.com/questions/53764754/model-aggregating-in-viewer-coordinate-issue