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Re: Making pt a non-physical unit

From: Brad Kemper <brad.kemper@gmail.com>
Date: Sat, 16 Jan 2010 11:28:43 -0800
Message-Id: <4F7CAB09-0994-4C40-B4A3-B47509A92974@gmail.com>
To: Giuseppe Bilotta <giuseppe.bilotta@gmail.com>
Cc: Ambrose LI <ambrose.li@gmail.com>, "Tab Atkins Jr." <jackalmage@gmail.com>, "robert@ocallahan.org" <robert@ocallahan.org>, www-style <www-style@w3.org>

On Jan 16, 2010, at 2:48 AM, Giuseppe Bilotta <giuseppe.bilotta@gmail.com 
 > wrote:

> On Sat, Jan 16, 2010 at 10:39 AM, Ambrose LI <ambrose.li@gmail.com>  
> wrote:
>> 2010/1/16 Giuseppe Bilotta <giuseppe.bilotta@gmail.com>
>>> If print vs screen is to be considered, I'd rather see it influence
>>> whether viewing distance should be considered or not, where print
>>> sizing would be unaffected by (assumed) viewing distance, in  
>>> contrast
>>> with screens and projections, where an estimate of the viewing
>>> distance can be done from the device size (an information typically
>>> available from the o/s). For example, an iPhone with a 160dpi (=5/3
>>> the CSS dpi) is usually held a 3/4 the distance of a typical  
>>> monitor,
>>> thus leading to a 1.25 (rounded to 1) correspondence between CSS and
>>> actual dpi.

Don't some Android phones have more pixels, but for a similar range of  
typical viewing? Wouldn't a Kindle be held at a similar distance, but  
with a larger screen and different pixel sizes?

>> But how do you estimate the viewing distance, even if only
>> approximate, for projections? In a large lecture hall or meeting  
>> room,
>> it would be a very large range, say 2–50 metres (from the first ro 
>> w to
>> the back row). Such estimates are useless.
> People sitting at extreme positions are going to have suboptimal
> viewing experiences regardless. So the question would rather be: what
> is the typical 'optimal' viewing distance for a projection with a 100"
> diagonal?

There may be a minimum distance to avoid having large device pixels  
from looking like mosaic tiles. But I think it is a "fool's errand" to  
try to pick an optimal distance. There is not neccessarily only one  
sweet spot, even if you know the size of the screen or projection.  
Some displays (of maps, for instance, and not neccesarily just  
geographic maps) could be designed to have useful levels of  
information at many distances. A billboard or outdoor signage might be  
designed to convey the message from a mile away or a hundred feet  
away, equally well. It might even have smaller print near the bottom  
for when you are close, and huge letter above that for when you are  
far away. It might even use some sort of lenticular technology to  
automatically show more detailed info as you got closer and your angle  
changed, without the device size ever changing. Or two billboards of  
equal height could have two very different widths, but similar ranges  
of good viewing.

Consider also a long hallwall, with the walls covered in a wallpaper- 
like OLED. On one side, the display is from floor to ceiling, and the  
other side has some chairs and cabinets and so starts from 4 feet up  
to ceiling. I use DIVs and CSS animation and a little JavaScript to  
move infographics and art and advertising around as you walk down the  
hallway.  What does the display size tell you about the optimal  
viewing distance? Nothing. I might have smaller, detailed info at head  
level, and big arrows or background images at farther distances, way  
down there by those two doors at the end.
Received on Saturday, 16 January 2010 19:29:36 UTC

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