#!F-adobe-helvetica-medium-r-normal--18*
#!N 
#!CSeaGreen #!N  #!Rall613 TV Line Resolution 
#!N #!EC #!N #!N Resolution losses are most evident if you 
use single-width lines. Workstations have both a higher number of vertical 
and horizontal lines on the screen, and a much higher "refresh" 
rate than consumer TV. However, on TV, the alternating lines (odd 
numbered, even numbered) are "refreshed" or painted on the monitor at 
slightly different times. As long as the scene contains objects that 
span more than one of these lines, our eye-brain system is 
fooled into believing that the entire object is always present, due 
to the phenomenon of "persistence of vision." But when you use 
single-line width horizontal lines, the lines will visibly flash, clearly showing 
that they are being drawn only half of the time. #!N 
#!N Related to this problem is the condition in which you 
rotate a grid of single-width lines slightly away from horizontal. This 
will generate an optical effect called a "moire pattern," in which 
curved lines appear where none are actually present, and, this frequently 
causes colors to appear that are not in the original signal. 
Both of these effects can be very distracting. #!N #!N Finally, 
single-width vertical lines will not have the same color! Because of 
the way consumer TV color phosphors are aligned, a vertical line 
at one location may be blue, but if you move it 
slightly it will become red. A grid with single-width vertical lines 
will appear to change color as you translate the grid in 
a horizontal direction. #!N #!N So what is the solution to 
all these problems? Do not use single-width lines, ever. Data Explorer's 
Tube module is the easiest way to fix most of these 
problems. Tube generates cylinders around any kind of field with line 
connections. If you have created a mesh of lines with ShowConnections, 
for example, you can run this visual object through Tube to 
"fatten" up the lines. Tube permits you to choose a diameter 
that looks right. As long as you make the tubed lines 
bigger than one TV line width, you will have solved the 
problem. #!N #!N Be aware that single-width line text or captions 
will become virtually illegible on TV. To get better-looking results using 
the "stroke" fonts (originally designed for plotters), you can use Tube. 
Another technique is to use a multiple-line font, such as the 
"roman_d" font supplied with Data Explorer. The best solution is to 
use an "area" font that is made up of characters containing 
polygonal faces rather than single lines. Data Explorer provides a font 
called "area," or "pitman," which uses polygonal faces. #!N #!N Another 
tip about text is that due to the much lower resolution 
of TV, you must be careful to keep text large! Ideally, 
use a size that permits only about 30 to 40 characters 
to fit across the width of the screen. Fine detailed text 
annotations may look good on the workstation, but will become blurry 
little globs on TV, defeating the whole purpose of annotating your 
video for your viewers. Try making some text in different sizes, 
then dub to VHS videotape. Can you still read the text? 
If so, the size is probably sufficient for general use. If 
it is too mushy to read, increase the size. For best 
legibility use white or yellow colored text. #!N #!N #!N  #!F-adobe-times-medium-i-normal--18*   
Next Topic #!EF #!N #!N  #!Lall614,dxall615 h TV Color Resolution  #!EL  #!N  #!F-adobe-times-medium-i-normal--18*   #!N 
