Are the marks on the ellipse template the only possible minor axis? Explain question in the comments
https://i.redd.it/do7yr4dnnq381.jpg
2021-12-05 14:59
GatoDoKapeta
GatoDoKapeta
2021-12-05 15:02
Its a shame I got to lesson 7 without fully understanding this, but my knowledge about minor axis is still kinda shaky. I understand minor axis as a line that cuts the ellipse in a half and goes to a vanishing point. So I think there could be other points in the ellipse that would cut it in a half besides the ones in the ruler, is it correct?
Uncomfortable
2021-12-05 15:33
You're missing one important property - it's the line that cuts the ellipse into two equal, symmetrical halves down its narrowest span. There is only one line for each ellipse that would qualify.
Your ellipse guide has a pair of markings for the major axis, a pair of markings for the minor axis, then one marking between them - not sure what it's for. But the one you want to pay attention to is the pair that crosses the ellipse's narrowest dimension. Basically where it's skinniest. On that photo, it's the markings on the left/right if each ellipse, rather than the ones on the top/bottom.
GatoDoKapeta
2021-12-05 15:58
Oh sorry, that makes sense, Im still confused though. What about this? I traced the minor axis as indicated by the ruler, I was following the truck demo and I think I redid it 3 times now and I still cant get it right. I thought I was understanding things when I was free handing stuff but now with the ellipse template Im very confused.
Uncomfortable
2021-12-05 16:41
There are two distinct elements to an ellipse - its orientation (which determines its minor axis, or you can look at it the opposite way and say the minor axis you want to align to determines the orientation), and the degree. In a case like this, you have your minor axis predetermined, and so there's only the degree left to play with. Of course, as you change the degree, then the plane that encloses the ellipse would also change.
This is because not all ellipses you add to a scene will actually represent a circle in 3D space, and not all planes you draw will represent a square in 3D space. Once you have some other elements down on the page, then there's enough information that helps define the scene itself, and the viewer's relationship to it, that you can no longer take an arbitrary ellipse and say "this is a circle in a particular orientation in the world".
That is largely what the cylinders-in-boxes section of the cylinder challenge focuses on. That is, we draw a bunch of boxes, and use the cylinder (or rather its 2 ellipses) to check if the ellipses' line extensions align with the box's line extensions. If they do, then that tells us that the ellipses are indeed representing circles that rest on the surface of the box, and that our estimated proportions for the box are in fact square in those two opposite planes which contain the ellipses.
More often, however, they won't align so perfectly, and instead we'll be able to see that our estimations were off, and therefore some adjustment should be done in the next page of attempts. Gradually doing this over and over is intended to sharpen your instincts, allowing you to pick more correct proportions for your boxes/planes, regardless of how they're oriented in the world.
GatoDoKapeta
2021-12-05 17:18
I still dont get how to apply all this to the truck demo I draw the plane to draw the ellipse inside, with one side open, then I draw an ellipse that tries to touch the corners of the plane (sometimes they get slightly smaller or bigger because of the jump in size of the template) and close it, but then the minor axis of said ellipse points to a place where I couldn't place another wheel and doesn't go to the vanishing point it should go (like huge difference from where it is going. If I try to position the ellipse in a way that its minor axis would point to a more correct place, it stops aligning the contact points vertically. I tried changing degrees but all of them had the same problem. so what do I do? How do I draw the other side of the cylinder? Im sure Im doing some kind of dumb misunderstanding but I read the lessons again and I still dont get it in practice
Trying to explain myself with a messy drawing
Uncomfortable
2021-12-05 18:00
Unfortunately I'm running short on time and have a ton of things to do, so the best I was able to do was throw together this diagram of how one might go about constructing what is in effect a cylinder, such that it aligns to a particular minor axis line.
The important part is really at step 3, where we're drawing our first ellipse such that it:
Due to its orientation, aligns to the given minor axis line
Due to its degree, touches those top/bottom edges at "contact points" which align towards the vertical vanishing point. Since we're drawing our vehicles with a vertical vanishing point at infinity, that means the contact points sitting directly above/below one another, so a perfectly vertical line would pass through them.
If this diagram doesn't clarify things for you, I'd recommend asking for more support over on the drawabox discord chat server.
GatoDoKapeta
2021-12-05 18:07
Thank you so much, this is much more helpful than I could have asked for, I really appreciate how you spend your time answering this kind of stuff for free here. Ill try again with this method :)
Ricen_
2021-12-05 23:06
I suspect that is just a line meant to point toward the size label for the ellipse.
canuckpopsicle
2021-12-06 09:27
I believe those extra marks are for when you're drawing a circle on a flat surface that's angled away from you. Example, drawing an oblique cube, you'll use the 45° ellipse, place that mark vertical on the side of the cube (not front or top of cube), center your circle where you want it, and use your pencil/pen to draw the circle. Viola.
Use the 60° one for isometric angled objects, so on and do forth.
Uncomfortable
2021-12-06 18:09
Huh, interesting. Thanks for letting me know!
Rookie007
2021-12-06 15:03
The paper folding technique is your friend if you are unsure cut out the shape and try to fold it in half no overhang