Establishing VPs and horizons in Landscape photos?


#41

Any chance you could send me that image? I’d like to try and work a few things out myself when i get a spare moment, as you seem to do a few things different to how i expected and i’d love to see whether i get the same results :slight_smile:


#42

Sure no problem, what’s your email?

edit - attached a tidier image which I knocked up in CAD, and you can see that my black linework (establishing converging lines from the photo) doesn’t line up on the horizon line perfectly - I wonder if this is due to lens imperfections or just error on my part? Perhaps I didn’t get the rotation perfect - either way, it should be good enough for my matte painting.


#43

Ok, after seeing your new perspective mock up, i’d say don’t send me the image. You confirmed my suspicion that the lines in the image may not vanish to the horizon. However, I think you also landed on the reason behind that - lens distortion. You’ll never get a perfect lineup with an image that has lens distortion. So really we need to test an image taken by ourselves, where we have all the lens info and can undistort the image before setting up the perspective…
I’m impressed that you’ve taken this so far already. Can you explain what the blue circle is representing? It’s possibly just a different way of working, but i’m not sure what that is being used for.
Great stuff tho, looks like you cracked the vertical vanishing point at least!


#44

The blue circle is the method to establish where your Auxilary CP is from your (Pink) horizon line (well at least I’m prtty sure that that is the case), I drew a smaller blue circle just to make it clearer where it’s centre is.

And the radius of the big blue circle is based on the yellow lines.

So now you could draw 45VPs from your Aux CP to where the blue circle intersects the pink horizon line.

I think for sketches and paintings, the error (perhaps because of distortion) is acceptable. I think for a future cityscape full on matte painting - 3D all the way from me however I’ve yet to actually test this by setting up a 3D scene. I will do though - just not at the moment.

I’ve found that there are a few different methods to establish VPs, and I’m prety sure that this method is more accurate than at least one of the other methods - and I have to say again: that is on the provision that this is correct of course!

I’ve derived this information from a book and this web page (search for Exact Horizon Line Method:

http://www.handprint.com/HP/WCL/perspect4.html


#45

What you have looks pretty good to me. The only real test will be with a 3d scene of course, but even a 3d scene i believe is only accurate up to a point. Like you said, the result you have there is very close, close enough to get away with it. And yes, 3D will always be quicker than going crazy and drawing all this stuff out manually, but it is great practice and training, I’ve learned a lot from all the questions we’ve been throwing back and forth in this thread.
By the way, that web page is gold! Great find. I’ll need a full weekend just to read it through without getting confused i’m sure, but its a great resource!

Cheers,
N


#46

Yeah for sure I’ve learnt a lot too - thanks very much for your input. That website is very detailed - I just scanned over the top of it until I stumbled across a diagram that looked similar to the method used in my book.

I think this will be a handy bit of knowledge to have - I’m going to have a breather from perspective learning though - on to the next challenge for now.


#47

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