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# how to draw calculated shadows on a plan or elevation by hand?

Gyo

anyone learned how to draw calculated shadows? or any books teach it?

please let me know!! thank you guys!!!

is time consuming but easy. wouldn't do it by hand anymore, but if you feel the urge below is from googely...

Shadow length of trees, structures, or topographic features can be calculated based on the height of the element and the altitude angle of the sun at a given time of day during a given day of the year. Typically, longest shadows in winter, and shortest shadows in summer are used for solar access calculations in northern latitudes. Shadow length is calculated using the formula:

Height of the element

Shadow length = tan (altitude angle)

Example:

Latitude is 36 degrees

Noon Sun on December 21 = 30 degree altitude

Shadow for 40’ (12000 mm) tree

= 40 / 30°

= 69.28’ the length of the shadow

Carl Douglas (agfa8x)

Get an old-school book on hand-draughting. It's too hard to explain without drawings. I'm sure one of Francis Ching's books will explain it well enough. There are at least two ways of doing it: the good-enough approximate method, and the technically correct method. Both take time. Even slower if you want to get actual sun angles involved, like jump is suggesting.

mleitner

If you draw shadows manually to add a sense of depth to an elevation or plan it is common to use a 45º angle (also 30º and 60º). Length of the shadows can then be drawn at 2/3 the actual length or the full length. This simple approach works well on relatively planar elevations and plans. Work yourself through the planes of your elevation and you will get nice shadow detail around windows and eves as well as in areas of setbacks.

xtbl

yeah, i second ching's books. particularly design drawing.

Charles Ellinwood

i agree with what everyone else has said.

you can also just underlay a copy of your plan offset the appropriate vertical and horizontal directions so you can just trace the outline of the shadow where the underlay's walls are located.

el jeffe

strlt_typ

or sciagraphy...

strlt_typ

use shadows to hide things you don't want clients to see...

Gyo

umm which ching are you guys talking about?
Or any other titles~?

thanks alot by the way guys!!

citrus.grey

The most accurate you'll get will be traced from a render, even a quick sketchup render will be pretty accurate.

You can measure shadows off a physical model if you have one of those charts where you move the desk lamp until the matchstick equals a particular length. You could probably get that on google somewhere. Can't recall the name of those now.

citrus.grey

Oh and Design Drawing is the Ching you want. (as mentioned earlier)

Carl Douglas (agfa8x)
Design Drawing

There are lots of other books that will teach you the same thing more or less.

plastic

i personally like " Architectural Shades and Shadows" by Henry McGoodwin (1904) we referenced it in a studio i took that dealt with the design of a building that started with shadows and progress to a physical form.

there are some interesting articles in the beginning dealing with more than how to render shadows on architectural. how understanding shadows are important in ultimately understanding form and space. a good read.

we used a facsimile copy in the studio and it took me quite some time following graduation to track down. unfortunately it was not a first edition like i had hoped, but it was a 1922 printing and it included dated and graded shadow assignments from a student at the university of michigan in 1924 (he was a B student).

dedubs

i second googling descriptive geometry.

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