cedricgoModerator
Sep '18

Hello Serfer!

Let me start by saying that I'm not completely sure if the answer I'm going to give you is actually the right one, but here I go.

First, you want to draw a 90 degree angle in such a way that the lines pass through your vanishing points and the angle is aligned with the corner that your lines create

Cubebrush_Serfer_Perspective001.jpg1200x865 52.5 KB

Next, starting from your vanishing point, you want to trace guidelines that will cut your line to the length that you want. Then do the same on the other side so that it crosses the previous guideline on the green line like in this example.

Cubebrush_Serfer_Perspective002.jpg1200x865 66.6 KB

And then where your line and the guideline crosses will be the length you want.

Cubebrush_Serfer_Perspective003.jpg1200x865 74.1 KB

Cubebrush_Serfer_Perspective004.jpg1200x865 43.2 KB

I hope this was clear enough and that it helped. But as I said, I'm not totally sure if it's the right method, so be careful.

Sep '18

Thank you very much! It seems very likely that it's the way to do it, altough if it's taken to extreme cases, the actual drawn lines can vary a lot, I did an example with the same lines in blue. But I supose it's due to the innecesary extreme perspective.

Perspective question 2.png1063x319 28.9 KB

Thank you once again for taking the time!

Sep '18

Weee! Perspective!

Cedricgo was almost spot on, but you cant use that vertical line as the back corner for any square that is not equidistant from the two vanishing points and vertical to the vanishing plane.

I wanted to really get how this works down, so here it is. As noted, this works best within the bounding plane of the vanishing points, I know that there is math that you can do when you are out of the bounding plane to make it work as well, however it is probably easier to do this part and then use the "Fence" technique that Marc outlined in Term2 Perspective 2.

But it also might just be better to eyeball it and go with what looks mostly right. You only need to do this crazy way for architecture.

I hope this is visible, I am uploading a file that is about 2k pixels wide.

... Yep! Just posted and checked. Click on the image once and it will come up all small, click on it again and you will have the full version flooding your screen so you can see and save it.

180926b.jpg2000x5917 1.08 MB

Hope this helps! MATH!

cedricgoModerator
Sep '18

Oh damn, I didn't even thought about that. You're right! Thanks for correctin me :smile:

@Serfer, peter-hartnett's method is what you need. You'll just have to do a little bit of reverse engineering to make it work with what you already have.

Sep '18

Thank you very much to both of you! that's super helpful!
By the way, for me it's super hard to get confident eyeballing perspective, because I always feel that the most minimum change in angle of any line, can result in a great mess, and I end up taking super long to do very simple images (the homework).