# timelapse. how they do this



## rambarra (Dec 3, 2012)

trying to figure out but no clue

https://vimeo.com/54734715


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## PhilippP74 (Dec 3, 2012)

Could be I'm missing your point, but here's what I would try:

Doing a 14s exposure already produced some short star trails on my night pictures, so going for an exposure time of 1-3 minutes should give you something comparable seen in the video.

The clip had a length of about 6s which at 25 fps is 150 frames. So in total something between 2h and 7h total shooting time.

To to timelaspe I'm using a hähnel Giga T Pro II or http://dslrcontroller.com/ on my Android phone.

Hope this helps


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## rpt (Dec 3, 2012)

My guess is that the person took a number of time lapse still shots. Say that variable is "l". To get the star trails, one needs to create a composite of a number of shots. Say that variable is "m". To run for "s" seconds, one needs say 25 * s composites. This is needed so that the frames do not look jumpy - jumping the whole length of the star trail...

Since it ran for 5 sec, we need 125 composites.
Since each composite is made up of "m" shots; if "m" = 5; composite 1 is made up of shots 1,2,3,4 and 5; composite 2 made up of shots 2,3,4,5 and 6 and so on till composite 125 is made up of shots 125, 126, 127, 128, 129 and 130. So "l" becomes 130. Now string the composites in a video editor and that should do it...

May be there is a simpler way though...


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## rambarra (Dec 3, 2012)

I was just guessing that if you, for example, make consequential 30 sec long exprosures you will add a segment to the top and delete a segment from the tail of the trail and it won't be a smooth movement as seen here


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## rpt (Dec 3, 2012)

rambarra said:


> I was just guessing that if you, for example, make consequential 30 sec long exprosures you will add a segment to the top and delete a segment from the tail of the trail and it won't be a smooth movement as seen here


Yup, that is why I think it is made of composites... 

If you put a mouse pointer at the end of a trail, it seemed to me that the frame advance was about 1/5 th. the star trail length; hence my magic number of 5...


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## joshmurrah (Dec 3, 2012)

rpt said:


> rambarra said:
> 
> 
> > I was just guessing that if you, for example, make consequential 30 sec long exprosures you will add a segment to the top and delete a segment from the tail of the trail and it won't be a smooth movement as seen here
> ...



this, definitely.

It's something like this: Take roughly 130, one second exposures. Then it's a startrail of 1-30 for frame 1, frames 2-31 for frame 2, frames 3-32 for frame 3...repeated roughly 100 times for the 4 seconds of video. Pretty cool effect but WOW tedious.


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## rpt (Dec 3, 2012)

joshmurrah said:


> rpt said:
> 
> 
> > rambarra said:
> ...


I am just plain lazy. So is there a software program to merge the individual exposures? Also, how did you arrive at the magic number of 32? BTW, I like 32 better than 5...


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## rambarra (Dec 3, 2012)

I'm struggling with my head. It is not that simple. You must take into account also the velocity at which the stars are moving.
If you make a burst of 130 shots (one per second) how much will star move in 2 minutes? A little bit.. but not that much. 

And if you make one shot ... then wait ... then make another shot then wait etc... you will end up having 130 intervalled shots, which will result in jumping footage...

I'm more prone to think that this is done via software during editing


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## pardus (Dec 3, 2012)

Way longer exposures, 30 sec or more and no delay between shots


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## bvukich (Dec 3, 2012)

pardus said:


> Way longer exposures, 30 sec or more and no delay between shots



No. The star trails overlap from frame to frame. This is rolling sets of N frames stacked, like joshmurrah said.


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## rpt (Dec 3, 2012)

bvukich said:


> pardus said:
> 
> 
> > Way longer exposures, 30 sec or more and no delay between shots
> ...


+1000
Do you know of a software that would merge "n" images given their file paths?


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## bvukich (Dec 3, 2012)

rpt said:


> bvukich said:
> 
> 
> > pardus said:
> ...



I'd write a shell script to do it. In fact, I probably still have some image series' left from last time I did a star time lapse, so I'll slap something together tonight. I'll share the scripts once I'm done. They'll be for Linux, but should be easily adaptable to a Mac. Sorry Windows users.


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## rpt (Dec 3, 2012)

bvukich said:


> rpt said:
> 
> 
> > bvukich said:
> ...


 
Thanks


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## samsettle (Dec 3, 2012)

Try using StarStax... software just for this. 

http://www.markus-enzweiler.de/software/software.html


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## bvukich (Dec 4, 2012)

I need to adjust the setting for enfuse, but this is what I have so far. It blends the images, ramping up to whatever the max is ($FILESPAN) then ramps back down at the end.


```
#!/bin/bash

FILESPAN=30
NUMBEROFFILES=`ls img_*.jpg | wc -l`
LOOPCOUNT=$(($FILESPAN+$NUMBEROFFILES-1))
for i in $(eval echo {1..$LOOPCOUNT})
do

CUTSTART=$(($i-30))
if [ $CUTSTART -le 1 ]; then CUTSTART=1;fi
CUTEND=$i
if [ $CUTEND -ge $NUMBEROFFILES ]; then CUTEND=$NUMBEROFFILES;fi

enfuse --output=eimg_$i.jpg `ls img_*.jpg | cut -d'
' -f$CUTSTART-$CUTEND`

done
```

I'll post something more final, which will also resize and make the movie later tonight.


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## rpt (Dec 4, 2012)

samsettle said:


> Try using StarStax... software just for this.
> 
> http://www.markus-enzweiler.de/software/software.html


That is interesting! Thank you.



bvukich said:


> I need to adjust the setting for enfuse, but this is what I have so far. It blends the images, ramping up to whatever the max is ($FILESPAN) then ramps back down at the end.
> 
> 
> ```
> ...


Cool! Thanks.


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## bvukich (Dec 4, 2012)

Here's my final script. Takes you from a directory full of images, to a movie. I've got it running on 139 images right now, but it will take at least another hour to process (it kills a quad core 2.4Ghz 8GB). It's just an image set I still had laying around from 2009, and not the greatest, taken on my trusty old XSi. I'll throw the video on Youtube when it's done and post a link.

For the resizing and video portion of the script, this may be useful: http://www.canonrumors.com/forum/index.php?topic=2838.msg59581

If you want help modifying the rest of the script just ask.


```
#!/bin/bash

FILESPAN=30
NUMBEROFFILES=`ls img_*.jpg | wc -l`
LOOPCOUNT=$(($FILESPAN+$NUMBEROFFILES-1))

for FILE in img_*.jpg ; do convert $FILE -background black -gravity south -extent 4272x2403 -resize 1920x1080 RE$FILE ; done

for i in $(eval echo {1..$LOOPCOUNT})
do

CUTSTART=$(($i-30))
if [ $CUTSTART -le 1 ]; then CUTSTART=1;fi
CUTEND=$i
if [ $CUTEND -ge $NUMBEROFFILES ]; then CUTEND=$NUMBEROFFILES;fi

enfuse --hard-mask --exposure-weight=0 --saturation-weight=0 --contrast-weight=1 --output=EFimg_`printf "%04d" $i`.jpg `ls REimg_*.jpg | cut -d'
' -f$CUTSTART-$CUTEND`

done

mencoder "mf://EFimg_*.jpg" -mf fps=10 -o TLapse.avi -ovc lavc -lavcopts vcodec=mjpeg
```


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## bvukich (Dec 4, 2012)

Still processing, but here ya go:

TLapse

Quite boring though, if the weather were cooperative this time of year I'd have taken a new series.


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## bvukich (Dec 5, 2012)

Some tweaks (and fixed a mistake). I have this running on the same series right now, but the increased resolution (4k) and number of files mean it'll probably run all night.


```
#!/bin/bash

FILESPAN=60
NUMBEROFFILES=`ls img_*.jpg | wc -l`
LOOPCOUNT=$(($FILESPAN+$NUMBEROFFILES-1))

for FILE in img_*.jpg ; do convert $FILE -background black -gravity south -extent 4272x2403 -resize 4096x2304 RE$FILE ; done

for i in $(eval echo {1..$LOOPCOUNT})
do

CUTSTART=$(($i-$FILESPAN))
if [ $CUTSTART -le 1 ]; then CUTSTART=1;fi
CUTEND=$i
if [ $CUTEND -ge $NUMBEROFFILES ]; then CUTEND=$NUMBEROFFILES;fi

enfuse --hard-mask --exposure-weight=0 --saturation-weight=0 --contrast-weight=1 --output=EFimg_`printf "%04d" $i`.jpg `ls REimg_*.jpg | cut -d'
' -f$CUTSTART-$CUTEND`

done

mencoder "mf://EFimg_*.jpg" -mf fps=30 -o TLapse.avi -ovc lavc -lavcopts vcodec=mjpeg
```


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## rambarra (Dec 5, 2012)

nicely done. thanks


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## emag (Dec 5, 2012)

A way for Windows users to maybe do it with, f'rinstance, Lightroom....

Say we're using 130 total images, each one a 1-5 minute exposure.

Stack images 1-5 and process. Unstack those, stack 2-6 and process. Unstack those, stack 3-7 and process. Rinse and repeat to the end.

Run the processed frames through a video editor.

Would be nice to automate this tedious process, though. There's probably some Windows compatible software out there that can be adapted.


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## emag (Dec 5, 2012)

*On second thought....*

.....this could do the trick

http://startrails.de/html/software.html


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## bvukich (Dec 6, 2012)

Final version. Rolling set of 60, and in 4k resolution for more stary goodness...
TLapse


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