DEVELOPMENT DRAFT     The only stable URL is http://www.vendian.org/howbig/.
Comments encouraged - mncharity@vendian.org (Mitchell Charity)
How Big Are Things?
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small Real
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big     solar system between galaxy
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meter
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Tera
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Exa

Calibrating...

Making things look the right size on your screen.
Computer displays have different resolutions.
To make things on these pages look their real size, this site can adapt to your screen's resolution.
The current setting is 2.95 pixels per millimeter, 75 dpi (dots per inch).

You can calibrate using a dollar bill, a metric or old-english ruler,
or a folded sheet of 8.5 x 11 inch paper.
Or, if you already know:
 
ppdm (between 280 and 420)     [for video projection: 450 to 950, by 50's]
  Finally, you can check the vertical calibration.

... using a Dollar bill
   
2.8 ppmm



3.0 ppmm



3.2 ppmm



3.4 ppmm



3.6 ppmm



3.8 ppmm



4.0 ppmm



4.2 ppmm

... using 100 mm
    100 mm
2.8 ppmm



3.0 ppmm



3.2 ppmm



3.4 ppmm



3.6 ppmm



3.8 ppmm



4.0 ppmm



4.2 ppmm

... using 6 inches
    6 in
2.8 ppmm



3.0 ppmm



3.2 ppmm



3.4 ppmm



3.6 ppmm



3.8 ppmm



4.0 ppmm



4.2 ppmm

... using 4.25 inches A sheet of paper (8.5 inch wide), folded in half...
    4.25 in
2.8 ppmm



3.0 ppmm



3.2 ppmm



3.4 ppmm



3.6 ppmm



3.8 ppmm



4.0 ppmm



4.2 ppmm

Double checking vertically...

Some screens have pixels which are not quite square.
For instance, they might be taller than they are wide.
Making circles look squashed.

Ideally, I would allow you to also callibrate vertically.
But I'm not set up to do that.
So the best you can do is check, and if it is annoyingly off, perhaps choose some compromise callibration.

    Dollar 100 mm 6 in 4.25 in
   

Choose a person height...

A person icon is used as a rough height reference.
You can use your own height:
    cm
230 cm
220 cm
210 cm   (7 ft)
200 cm
190 cm
180 cm   (6 ft)
170 cm
160 cm
150 cm   (5 ft)
140 cm
130 cm <-- current
120 cm   (4 ft)
110 cm
100 cm
90 cm   (3 ft)
80 cm
70 cm
60 cm   (2 ft)

You are done!

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Noncommercial use is fine. Otherwise, ask.