[net.sources.bugs] M.C.Escher "Square Limit" Picture.

edward@ukecc.UUCP (Edward C. Bennett) (07/25/86)

In article <1686@eagle.ukc.ac.uk>, msp@ukc.ac.uk (M.S.Parsons) writes:
> 
> PICTURE FORMAT
> The original format for each drawing is simply a list of line specifications,
> one per line in the form: x1 y1 x2 y2. To reduce the size of this file, these
> absolute coordinates are converted into relative coordinates. Then the file
> is compressed using compress (V4.0). Finally the file is uuencoded. So to
> view the picture: uudecode the picture file, uncompress it, pipe it through
> the relative to absolute coordinate filter and display on your favourite
> device.
> 
> PICTURE SIZE
> Bytes
> 94553  fish1
> 66278  fish1.r
> 20090  fish1.r.Z
> 27703  fish1.r.Z.uu
> Number of lines:        5973
> Min x and y:            0 0
> Max x and y:            1024 1024
> 
	Somewhere between England and Kentucky the picture files got
munged.
	I'll describe the problems with fish1. 'fish2' acted similarly.
Comparing the file sizes, my .Z file was the correct size so I thought
everything was OK. But after uncompression my .r file was 3 bytes too
small. Examination of the file revealed 8 munged lines, all ending with
a '-'. e.g.

16 11 -3 -

Sometimes the next line contained a lone '2', sometimes it was blank.

I tried just joining the two lines, adding a '2' if the next line was
blank, but that didn't work. Apparently, the problem is in the encoded
file.

	Has this happened to anyone else? Could this have been caused
by the BITNET? (Our news arrives via BITNET.) Would someone out there
who has this working be willing to mail me (UUCP) their copies of
the .uu files?

-- 
Edward C. Bennett

UUCP: ihnp4!cbosgd!ukma!ukecc!edward

Kentucky:  The state that needs a lottery to educate it's children.

"Goodnight M.A."

zben@umd5 (Ben Cranston) (07/27/86)

In article <547@ukecc.UUCP> edward@ukecc.UUCP (Edward C. Bennett) writes:

> ...Somewhere between England and Kentucky the picture files got
> munged.
> ...Could this have been caused
> by the BITNET? (Our news arrives via BITNET.) Would someone out there
> who has this working be willing to mail me (UUCP) their copies of
> the .uu files?

I can FTP the files down to UMD2 and send them via BitNet.  It is quite
possible that truncation to 80 column format when the message was passed
to BitNet is the culprit.  Mail on BitNet is a virtual punch file, and we
all know virtual cards can't have more than 80 columns, right?

I got the small fish to work OK, but when I try to print the big one the
Imagen (8x300) says "print error" and seems to lose itself in the complexity
at the top and bottom of the page.  Anyone else seen this happen?  Is there
some easy fix?
-- 
                    umd5.UUCP    <= {seismo!umcp-cs,ihnp4!rlgvax}!cvl!umd5!zben
Ben Cranston zben @ umd2.UMD.EDU    Kingdom of Merryland Sperrows 1100/92
                    umd2.BITNET     "via HASP with RSCS"