Photomatch pre work

thomthom · 2 Apr 2008, 07:41

I noticed this in the SU help about Photomatch

Barrel distortion typically comes from wide angle lens cameras, and users should use a third party product to eliminate it from images prior to using them within SketchUp. All cameras have a little bit of this distortion, typically worse around the edges of the image, and we have a simple tool for compensating for this visually.

In Photoshop, would that mean using the Lens Correction tool? Or is there other tool to use?

And don't I risk warping the image so Photo Match doesn't really work? Since cropping an image affects Photo Match...

pilou · 2 Apr 2008, 11:47

You must use tools transformation like Perspective, Deform etc...for have straight verticals
It's a cool thing to make a copy before all works

thomthom · 2 Apr 2008, 12:52

But the manual also says:

@unknownuser said:

Warped images. Images which have been manually warped via an image processing program, or specialized camera are not supported. For example, some cameras used for architectural photographs adjust for vertical perspective distortion, by tilting the camera plane. The resulting photo is an image similar to our “Two Point Perspective” mode.

It recommends adjusting the image while at the same time saying it causes problems.

confused

pilou · 2 Apr 2008, 14:37

Your problem is curious
It's better to have a photo with 2 points perspective !
And better have one measure somewhere
So no problem

if your photo has 3 points use a deformation tool for redraw it

Julius · 2 Apr 2008, 18:09

i've noticed that it's better not to shoot photos which are going to be used for photomatching with wideangle, because they cause a slight fisheye-like effect.

thomthom · 3 Apr 2008, 09:21

Thanks for the tips.

Unfortunately I have to work with less then ideal setup for Photo Match. I'm matching up a building into surrounding context so it's a large area, leaving any possible square angled objects/buildings very small. And some of the perspective required doesn't provide any 45 degree view points either. Doesn't help that it's an old city with basically no 90 degree angled corners.

While I can take new photos, the location is in fact right outside my office, the camera at disposal is just a small digital camera with no option to change lense. I hope to be able to get the office to get a better camera, alas it won't help me now. (Though any tips here are welcome.)

Some of the images I have seem to be have a very odd perspective. I'm wondering it's due to the zoom. Enhancing the warped effect?

twharvey · 5 Apr 2008, 07:01

Thomas,

I frequently have similar problems. With bushes, trees and inconvenient property boundries, I can't always get a square shot at the face of the building. I use PaintshopPro (a lot cheaper than Photoshop) to work the photos. I've noticed that the doors and windows are the most problamatic issues for realism. When you photograph a window from the side angle, you only see one side of the frame. This looks strange when the perspective is corrected. So, I now make a habit of getting cloe up shots of window and door details. I can then correct the distortion in the main photo and paste the close-up of the window into place. The result works pretty well. In extreme cases, I've built a whole wall from bits and pieces of other photos, like stone walls or bricks.

The other thing I often find useful when a wall has lateral symmetry is to get a good shot of one half and then paste the mirror image into the photo for the other half. With a lttle touching-up this looks OK.

Tom

twharvey · 6 Apr 2008, 06:18

Cheers, Modelhead!

Re cameras: I use a cheap digital camera with a built-in lens. It would be nice to have a good one like Modelhead describes; maybe for the future. The important thing is that, if you want realistic models, you need to spend a lot of time with your Photoshop type program to get the textures right.

gata · 7 Apr 2008, 06:13

Some people like the plugin PTLens to correct photo distortion http://www.epaperpress.com/ptlens/

Gaieus · 7 Apr 2008, 06:18

There is a little software (freeware) "GML Undistorter " which will straighted the barrel like sides of buildings. I don't know however if it distorts and destroys the image so it cannot be used in PhotoMatch (which I haven't really played around with yet to be honest).

thomthom · 7 Apr 2008, 09:17

I've managed to match the photos close enough now. I took some extra time to model some extra surrounding buildings for reference and ensure their height was correct. That helped alot.

I don't use PhotoMatch to model buildings or extract textures from, just to get the correct perspective for the model so I can drop it into Photoshop and then work on it from there.