Origin problems with photo matching


#1

I’m building a model from several photographs. The origin for my model is at an easily identifiable point, and everything works great for the first 5 or so photos. When I add additional photos, the yellow box representing the origin is outside of my model in a location that is not consistent with the origin in my model. This makes it very difficult to correlate the model to the photograph since I have to move the origin to a somewhat random position to get the model to overlay. What is happening here?


#2

Does this happen regardless of what photo you try to import, or only with some specific photos (trying to isolate whether the problem is with SketchUp or with the photo)? If it is just certain photos, might they have a transparent margin around the real image contents?


#3

Your photo is too close - it’s much easier if you can ‘see’ the origin in every photo you use. You can zoom out reallllllly far and try to move the model into place, but that requires pinpoint accuracy and a good bit of luck.
Note that SU does not take into account the parallax (curvature) of the lense, so trying to match geometry at the edges of the photo will probably not give the same results as stuff in the middle of the photo.

What you can do is make the model a component and copy it so that the origin is in a convenient place - put it on a separate layer and use the scene manager to turn on/off the relevant layers/models.


#4

It’s happening after every additional photo I add.


#5

I don’t think that’s it, some of the additional photos are taken from the same distance as earlier photos. I can also see where the origin should be in the photo, the issue is that the origin is no longer at that point in the model to align on the photo. For example, say my model origin is at the corner of a house. The first bunch of pictures work fine, I align the model corner of the house with the picture and adjust the vanishing points. The problem is when adding additional photos, the model being overlaid on the picture suddenly has the origin out on the sidewalk.


#6

I deleted all of the weird photo matches and started adding them again - so far things seem to be behaving correctly. I don’t really know what’s different, but I’ll try to pay attention to future issues. Thanks guys.


#7

It is possible to “flip” the model and have it do weird things by making the vanishing point go off to infinity and back again (taking the end point of one of the green/red construction lines and pulling it in the “wrong” direction.) You can also get weird things happening if you move the yellow vanishing point.
I have found that it works best if I position the camera/model so I am in roughly the right spot before importing the image to photo-match.


#8

Thanks, maybe that’s what happened. Some of the photos required some flipping of the vanishing points to get the model aligned and maybe something got screwy along the way.