therion and contours

[Wookey]

+++ Erin Lynch [04-03-01 20:18 -0800]:

>> Hi Wooks,
>>
>> Just wanted to let you know that we're thinking about using Therion to
>> trace contours and then writing a script to convert from Therion to
>> survex legs.


Interesting idea. If you need this then maybe Therion should incorporate
something like it more directly, although I'm not sure how exactly...

>> It should be doable, but we're having a few problems with
>> our installation of Therion. The biggest one is that if you zoom in on
>> a big map the whole thing just becomes unfeasibly slow.  Dunks thinks
>> it's probably making a bitmap (or something) of the entire image at
>> high res, which is why it's so slow.  Any ideas?


Yep - that's right, in fact there is more than one copy. I found the same
problem. (on a 64MB machine attemting to zoom to 200% on a 4MB scan makes
the whole thing disapear in a puff of smoke). Complaining to the Therion
list elicited this explanation:

>> 200% of 3.8Mb = 4Mb original image + 16Mb scaled image + 20Mb canvas RGBA
>> buffer = 40MB = 60% of RAM. This may be a problem, especially on some
>> operating systems.


The problem is that tcl's functions are used for the image management. tcl
stores images internally as full RGB, so making them b/w or greyscale
doesn't save any RAM, and it doesn't do anything clever like
image-manipulation programs to only expand the visible tile. Something could
probably be done to improve this but it's not trivial. This is a tradeoff of
using a quick-prototyping language for the GUI rather than doing it the hard
way.

For the tme being you need to work with either a machine with loads of RAM or
smaller images. Some work to see if TCL's handing can be improved in this
regard would also be a good idea. I agree it's a serious problem, stacho
doesn't seem entirely convinced yet.

>> The other problem is that the lines, control points and handles are all
>> a bit too chunky to be useable.   Any idea what magic rune we need to
>> change in order to make them a bit smaller?


Nope - ask the list - they are _really_ helpful. (the ctrl modified lets
you place points very close to other points which helps with the 'can't
zoom' problem).

cc:ed to Therion list

Wookey
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