UBASIC/Scripts:Time Lapse Photography

From CHDK Wiki

A really simple script for time lapse photography (as a replacement for the one in movie mode). Takes pictures at the given interval (using get_tick_count for accuracy), or as fast as it can (if the interval is too short).

Although this theoretically allows you to take time-lapse photos as large as you like, I recommend setting the image size down a bit, especially if you're shooting under 2 sec/shot, cause the camera takes a while to process/save the image, which might screw up your timing.

NOTE: On my PowerShot SD1000, you can only shoot pics that require flash in auto-flash mode and pics that don't require flash in no-flash mode. It does not take photos if your camera is in auto-flash mode but does not need to flash. If you try, the camera kind of stalls and doesn't do anything. Solution: set the flash mode to whatever you're expecting on your route. If you're attaching your camera to your bike, turn flash off before you start taking photos.

rem Time Lapse Photography
rem Step 1: Mount camera on bike
rem Step 2: Click "shoot" button
rem Step 3: Profit!

@title Time Lapse Photos
@param a Interval (secs)
@default a 1
@param b Interval (1/10 sec) 
@default b 0
 
i=a*1000 + b*100
if i<100 then let i=100
t=get_tick_count

rem Shot counter
n=1

print "Time Lapse Photos"

sleep 1000
goto "shot"

:shot
  t=get_tick_count 
  print "Shot", n 
  shoot
  n=n+1
  rem Wait i msecs, including the
  rem time it takes to shoot. 
  rem Shoots as fast as possible if
  rem each shot takes longer than
  rem i msecs. 
  d= i - get_tick_count + t
  if d<0 then let d=0
  sleep d
  goto "shot"