Line Drawing with Z interpolation

Line Drawing with Z interpolation

Post by E » Tue, 13 Feb 1996 04:00:00



Hello

    I need an algo that given to vertices X0,Y0,Z0 and X1,Y1,Z1 will

   not only draw a line (I am already using Bresenham's algo), but

   will also interpolate the Z values  between Z0 and Z1.

  I need this inorder to do  ZBuffering on a Line. I already have it

  working on polygons.

                                        Thanx in advance

 
 
 

Line Drawing with Z interpolation

Post by Jorge Acereda Mac » Fri, 16 Feb 1996 04:00:00



> Hello

>     I need an algo that given to vertices X0,Y0,Z0 and X1,Y1,Z1 will
>    not only draw a line (I am already using Bresenham's algo), but
>    will also interpolate the Z values  between Z0 and Z1.

Do you need an approximation or an exact method?

You can try with a one-dimensional spline forward
differencing algorithm (fast but only an approximation).

Greets,
--
 ---------------------------- --------------------------------------------
|       Jorge Acereda        |      Dream the same thing everynight       |

|       Intel Outside        |     No locked doors, no windows barred     |
|        Amiga Rules         |   No things to make my brain seem scarred  |
 ---------------------------- --------------------------------------------

 
 
 

1. Adding colour to scanned line drawings for CMYK printing Adding colour to scanned line drawings for CMYK printing Adding colour to scanned line drawings for CMYK printing

I'm trying to come up with the best way to colour
scanned line drawings
for a CMYK brochure laid out in Quark 4. The
drawings consist of only black
lines, and I want to add a flat colour "behind"
the lines, or perhaps
several flat tints of that colour.

Redrawing in a vector illustration package is not
an option.

Here is what I have done so far:
The line drawings have been scanned at 300dpi
100%, cleaned up, converted
to CMYK and a Threshold operation applied - in
other words, they consist of
only 100% black and 100% white. It's easy
colouring this using only
non-antialiased tools (e.g. Pencil and 1-tolerance
non-antialiased magic wand)
in Photoshop, leaving the black
lines untouched. They're saved as TIFFs. I've
printed separations from
Quark of a sample picture prepared in this way:
the black lines appear only
on the black plate, and do not knock out the
coloured areas on the other
plates. If there were any grey component in the
lines, they immediately
separate onto all 4 plates.

Here are my questions:
1. I'm worried about registration/trapping issues.
Do the coloured areas
stop just *inside* the outer black line containing
it? In that case, will
it not be very sensitive to misregistration?
2. Why aren't the coloured areas knocked out by
the black lines? Surely a
TIFF is entirely "flat", and there isn't anything
telling Quark the the
colour continues "behind" the black lines?
3. Can one ask a repro house to trap imported
TIFFs like these? Specify a
0.1mm spread on the black plate *just for the
imported drawings*?
4. Is it best to have the black lines only in the
black plate? This also
means there will be a notable difference in black
"colour" between where it
overprints the other colours and where it doesn't.
5. Tints: I'm using the same CMYK Pantone colours
in Photoshop as in Quark
- I expect they will print identically. For a 50%
tint of a colour, I fill
a blank layer in Photoshop with that colour, set
opacity to 50% above a
white background, and pick up the result with the
eyedropper. Will this be
identical to a 50% tint in Quark?

Or, perhaps, does someone out there have a tried
and tested method for
doing what I'm attempting here?

I'd appreciate it enormously if someone could help
me out.

Thanks,
Francois

Sent via Deja.com http://www.deja.com/
Share what you know. Learn what you don't.

2. GLUT 3.4 available!

3. Drawing different line types at different line width

4. 2D GDSII or CIF to 3D model file

5. Draw polygon face and line in one line

6. Using MMX for blurring

7. Drawing non solid line with line width greater than one

8. HELP: Line drawing routine does not draw right.

9. ati radeon 8500 (line drawing and point drawing)

10. interpolation between two straight lines

11. What about exact line interpolation?

12. Line/Curve Interpolation from points