Sorry … it is basic stuff, but I just want to make sure I’m doing this correctly. Thank you again.

Yeah, I had a lot of trouble with that at first if you’re talking about that sight-sizing technique. The person who taught me it insisted that I use only a pencil or brush, because I would presumably always have one of those if I was out trying to produce art. The idea was to sight down your fully extended arm to the horizontally held pencil, while making sure to maintain the exact point of view as much as possible. A “key” measurement was then chosen from the scene with the thumb as the mark on the upright pencil.

I was horribly clumsy at it and still get stumped sometimes when I try it, but it makes a huge difference when I’m able to get a handle on it. Most of the time when I’m just doodling I’ll skip it and say, for instance, “Well, the front door looks to be about half the height of the building, so I’ll make the building two doors (keys) high.” And the building might be 5 (horizontal) doors wide or whatever, etc.

Is this even what you’re asking about? If so, the angles are a matter of visually aligning the pencil with the angle (maybe a pitched roof, for instance) in the scene from your same position, then translating that to your drawing. I hope I’m not as bad at describing it as I am at doing it:confused:

You can’t transfer the straight on (or close to that) width to a perspective side. While I am absolutely sure there is a mathematical formula, it all is going to depend on where your horizon line is in relation to your eye view. Short answer would be no. However, you can use the explained method to get a basic size.

One corner of the box (house,cube, etc) is going to be visible and closest to you. Find a “key” vertical dimension – door,window, etc and take a relative vertical measurement from that. Then see how many or what percentage of that the reference back is up or down from the side chosen as your corner’s top or bottom. Boy that’s complicated to say! What I’m saying is that you can see where the back wall/side is relative to the front side – duplicate the angle of the side from the front and you can get the relative location of the corner be it higher or lower than the top/bottom of the front side. It would be so much easier if I had a pencil, paper and scanner handy but I don’t … words really don’t help a lot in this I’m afraid. Perhaps you can grasp what I’m trying to say …

The front corner wall is X high. Presumably the back corner is also X high – but, due to perspective, it is higher or lower than the front wall. Figure that angle of difference and you can then use a relative “key” to determine exactly how much higher or lower it actually is. Should give you a pretty good approximation of width.

Whew! I’m glad that someone more knowledgeable and articulate jumped in to help you out! I’m actually downright stupid about that kind of spatial reasoning, but the sight-size technique did make a surprising (to me) difference in my cartoon-y way of drawing in terms of graduating to a more-or-less believable representational style. It can be a powerful tool for a beginner. I’m ashamed that I didn’t really practice it seriously.

The ideal as explained to me was to become skilled enough with the method to a point where one was capable of making the measurements on the fly without necessarily resorting to a tool. Skilled eye-balling, in other words.

One more thing: look for online how-tos for a DIY proportional divider. Seems like that would be the killer tool for sight-sizing. I think it would have helped me with the clumsiness I had with using a pencil to translate the measurement to the page, but the person who taught me the method strictly forbade it as a crutch for spoiled, gadget-crazy Americans

I posted that last one a bit too soon. I also meant to add that I don’t use any measurement device (like dividers). I spend a lot of time getting my reference feature placed and sized properly – generally the left side eye. Then I will work my way outward from there very slowly paying attention to angles and distances based on my reference eye. I emphasize the slowness here … if I get to going too fast I’ll miss measure something and then I’ll need to fix it later – besides everything builds off what came before so if I miss draw an area everything else will be off. Much like a building foundation. If you get it wrong everything builds from it so the entire building will be wrong.

I would use the same process if drawing a house or a box or something similar. Get one wall just right and then slowly move outward paying close attention to angles and distances – and measuring those relatively based on what I already had done. There is nothing speedy about my method of drawing and no short cuts so it’s definitely not for everyone but I do get basically acceptable results.