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Tobi Wulff Photography

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RAW Timelapse Workflow with Darktable and Davinci Resolve

I shot a new timelapse in the mountains, this time exclusively recording all the frames in full resolution and RAW (unlike my previous outdoor timelapse). It was recorded with the Olympus OM-D E-M1 (de) and Olympus 12-40mm F2.8 PRO (de) lens.

Out in the field

Basic outdoor timelapse 101: all manual settings, that is ISO, white balance, aperture, shutter speed. White balance was obviously daylight and I kept the ISO at its minimum (200). Shutter speed should be set to something "video-like". Video and film cameras usually use something called a 180 degree shutter which essentially means that the shutter speed is 1/(2 x frame rate). So for a 24 fps video that means 1/48 or (because photo cameras usually don't offer this setting) 1/50. Anything faster than that runs the risk of making the timelapse feel jittery and too sharp. For fast movements, like people or clouds, I like to go even slower and aim for something like 1/20 - 1/40. This gives the video a more dreamy and pleasing look.

I record every frame in RAW. I like to store JPEGs as well so I can generate a quick timelapse when I get home without having to go through the RAW workflow (described below) first.

To do the actual timelapse recording, there are several option depending on your circumstances and your equipment:

  • Using the camera's in-built timelapse function: most compact solution and works well on the E-M1 except when you want faster than 1 second intervals;
  • using a remote shutter release or remote timer: works great but you have to dial in the intervals using the anti-shock functionality and it's an extra cable flapping in the wind;
  • a slider or panning head triggering the camera: whenever the E-M1 sits on the panning head (see next section), it will receive it's shutter releases from the Genie. The result: accurate intervals perfectly timed with the stops between motions of the moving parts of the timelapse setup.

For filters I often use a graduated ND filter to make the bright sky and the darker ground a bit more even. This is particularly important at sunrise and sunset because the ground will be really dark. I also have a circular polarizer that lives on my lens 95% of the time: vegetation looks more lush, colours more vibrant, and annoying reflections of leaves or glaring surfaces disappear. It can also cut through a lot of haze and mist on a more cloudy day. Time in Pixels just released an excellent article about filters for video with many visual examples.

Getting moving

I've written about my DIY slider before and it is actually undergoing some major upgrades right now to make it more usable and flexible. However, I don't usually take it very far because it is heavy and big. In order to have something that always fits in even the smallest bag, is compact and rugged (not weather-proof, though) and "just works", I got myself a Genie Mini which is actually being developed here in NZ. It's controlled from a smartphone via Bluetooth so setting it up takes a few minutes since my phone is usually off when I'm in the outdoors (no reception anyway) but it's very intuitive and flexible (watch the videos on their website). All the shots in the video at the top of the page that have some side-to-side movement are done with the Genie Mini.

RAW workflow

The out of camera JPEGs are alright but (especially for landscapes) don't look nearly as good as they could when I develop my own final images from RAW: better colours, more dynamic range, more wiggle room in the highlights (and some in the shadows). This is particularly important when photographing sunsets, sunrises, or rapidly changing lighting conditions because the exposure can be adjusted so much in post. I load all my RAWs from one scene into Darktable, then do all my adjustments on one of them (shadows, highlights, general exposure, Velvia/saturation filter, contrast, noise reduction, but no cropping - I can always do that later when editing the video). Then, I copy the settings to all the other RAWs and export everything to bitmap files with a high bit rate, such as 16-bit PNG or TIFF. In theory, one could also make fine adjustments to individual frames at this stage.

Editing

The last step is to edit the photos into a timelapse video and maybe add some music and sound effects. I mainly use Davinci Resolve for editing because it also has colour grading built in but the colours should already be fairly correct and good looking from the last step. Davinci can directly import image sequences (i.e. individual files) and display them as video clips.

Please use the comment section below or head over to Google+ or Twitter @tobiaswulff to discuss this article or any of my photography and videography work. My Flickr, 500px and Vimeo pages also provide some space to leave comments and keep up to date with my portfolio. Lastly, if you want to get updates on future blog posts, please subscribe to my RSS feed. I plan to publish a new article every Wednesday.

Long-run timelapses across multiple seasons - Part 2

In the first part of my timelapse blog series I wrote about different types and techniques for longer and really long (seasonal) timelapse movies. In this article I want to describe a few specific techniques and tools that are useful (and often mandatory) to finalize those timelapses.

But first I'll lead into this timelapse article with my new video "Mountains and Clouds 2015" that I've shot over the course of about one year in the South Island of New Zealand on various trips.

One thing I wish I had done from the start is shoot all the frames for timelapses in full resolution and as RAW files. Always keep future use of your files in mind! Unless I got lucky and the scene was really well exposed, I couldn't correct as much as when grading from RAWs and because of the better resolution the final video will also look sharper. I take bets on Twitter (@tobiaswulff) on which scene was the one shot in RAW ;) .

Batch Processing

The first step to processing timelapse RAW frames is to "develop" them from being a digital negative to a bitmap photo file. When exporting the image it is important to choose a format that will retain the full bit depth of the original RAW file: options are TIFF or 16-bit PNG. JPEGs should not be used since they only store 8-bit of color depth which will not fare well in color correction and grading later.

There is another way, though: keeping the files in their RAW format and using a video editing software that can deal with RAW footage, such as Davinci Resolve 12. For Resolve to ingest the RAW files they have to be converted to DNG. My photo management software of choice digikam has an in-built DNG converter and I believe so does Apple Aperture, Adobe Bridge and/or Lightroom. While working with a RAW video is pretty neat, because this is not a recognized format from a video camera (such as RED) the possibilities to adjust the image are limited and a proper RAW photo program such as Darktable or Lightroom is much better suited for the job. Nevertheless, you are importing 10+ bit image data into the editing/color grading software which gives much, much more room for colour and exposure adjustments.

Compile Videos

As described earlier, Resolve can ingest DNG RAW files so it is possible to do editing and color grading with the source material. For the timelapse video posted at the beginning of this article, however, I compiled each sequence into a video first, which can be done using one of the following two Linux programs: Blender or ffmpeg (CLI tool). This use of "baked" videos will make the edit smoother because the program doesn't have to deal with as much data.

ffmpeg is a command-line tool, so it is easy to batch-process or automate converting image file sequences into video files. ffmpeg supports all the usual video file formats and containers, including ProRes which is a 10 to 12-bit 4:2:2 or 4:4:4 codec and the preferred format for Resolve. However, I found that the picture didn't quite come out the way I wanted, in particular darker areas got too dark so for example stars in night time sequences (like the one at the end of my video) almost disappeared. I'm sure this can be adjusted using the codec settings but for now I have turned to Blender.

Blender is first and foremost a 3D modelling and animation program. However, in recent years it also became a more and more powerful video editor and VFX pipeline, and it can be used to turn any bitmap sequence into various video formats. Once an image sequence has been imported, it can be modified (scaled, rotated, color corrected, composited with a 3D scene, etc) using nodes as shown in this screenshot:

For exporting I chose AVI RAW since it gave the best quality and could be converted to ProRes for Resolve, again without any loss in quality. It might be possible to export directly to ProRes or to use ffmpeg under the hood but I haven't explored the export and encoder settings too deeply yet.

Long Timelapse Processing Techniques

The biggest problems with long-term timelapses in the outdoors (i.e. outside a controlled environment) are changing lighting conditions and that it's basically impossible to get the camera set up 100% exactly the same way every time: the tripod will be positioned slightly differently, a zoom lens will make the focal length setting inaccurate, pointing the camera at the same spot will still be a millimeter or two off ... Luckily, both issues can be dealt with fairly successfully in software as described below.

Stabilizing and Aligning Photos

In order to make the transition from one frame to the next as smoothly looking as possible, non-moving objects in each frame really shouldn't move or jump around. Therefore, it is necessary to either align all the photos before they are compiled into a sequence (or video), or to stabilize the final video. There are at least three very different ways to achieving this. These different approaches can differ greatly in terms of time and effort, and quality of the end result.

1) Align photos automatically using Hugin. Hugin is an HDR and panorama toolkit but it can also be used to align a sequence of photos without exposure bracketing or stitching them into a panorama. There are several algorithms to choose from when aligning photos (I usually use "Position(y, p, r)" but its results are not perfect). The algorithm will look at all the photos that are next to each other in the sequence and find common control points in the picture that it uses to align (translate, rotate and scale) them. Control points can also be manually added, removed and shifted to improve the alignment. In terms of speed this is the easiest and fastest approach. I usually roughly follow this tutorial - something you will need because it's a complex piece of software!

2) Align photos by hand in GIMP (or Photoshop): there are various plugins for those image editing programs that allow a user to specify two common control points in two pictures and the plugin will then do the alignment. The results are near-perfect but it will take a long time because you have to do it for each frame in your sequence (what's that - 60, 90, 200?). A professional suite like Adobe's probably contains automatic tools similar to Hugin as well.

3) Stabilize the final video: all professional editing and/or VFX programs such as Resolve, Hitfilm, After Effects and also Blender have built-in stabilizers. I haven't tested this method yet but because they work on a frame-by-frame basis they should be able to stabilize the footage very well. However, as described in the next step, I like to blend (or blur) my frames which will definitely make stabilizing the video more inaccurate so doing it before the video is compiled seems more robust to me.

Blending Photos

As shown in some of the examples from other photographers in the first timelapse article, we often simply blend images or videos together to make for a smoother (and longer) final product. This can either be done between sequences (say you show a locked down timelapse of autumn, then blend it into another timelapse of the same spot in winter) or between every single frame. Using the free toolkit ImageMagick, this can be done with one command:

convert frame_a.jpg frame_b.jpg -evaluate-sequence mean frame_ab.jpg

Ideally, your original source files would be organized to have odd sequence numbers (frame001, frame003, ...) and the generated blended images will fill the gaps (frame002, frame004, ...). This way you'll end up with all the frames for the timelapse video, now much smoother because even though lighting conditions and your camera setup change dramatically between each frame, there is now a frame in between that combines both conditions and makes it look much more pleasant on the eyes.

Conclusion

As you can see, there is quite a difference between the blended and the original image sequence - apart from the speed that it loops at of course since one has twice the frame-count of the other. Note that this is not a perfect alignment and also that I haven't done any RAW processing yet (these are simply out-of-camera JPEGs) so for a final product I would first process all the frames so that they are similar in exposure and saturation. Left is original (rough and unpleasant), right is blended (smoother):

Please head over to Google+ or Twitter @tobiaswulff (see links on top of the page) to discuss this article or any of my photography and videography work. My Flickr, 500px and Vimeo pages also provide some space to leave comments and keep up to date with my portfolio. Lastly, if you want to get updates on future blog posts, please subscribe to my RSS feed. I plan to publish a new article every Wednesday.

DIY Motorised Dolly Slider

Motorised sliders (or dollies) bring motion and a nice parallax effect to timelapse shots. Commercial sliders have the advantage of being well built (hopefully roughly proportional the amount of money spent) and easy to set up. On the other hand, costs for rails and card alone can be several hundred dollars and adding motors and a control unit quickly pushes it $1000.

A home-made DIY slider can be made with $150-200 for materials and the Arduino board or other micro-controller, depending on what you already have lying around. I'd like to take mine hiking more often but it wasn't built with minimal weight in mind so this is definitely a point where a good commercial carbon-fiber slider and a cart with less metal could come into play one day.

There are many different designs out there but the biggest distinctions between them are:

  • continuous motion vs stepper motion
  • two rails vs monorail
  • motor mounted on end truss vs motor mounted on the cart

Continuous motion is cheaper because a very simple motor can be used and the expensive timing belt can be replaced with a wire to pull the cart. However, this does not work for longer exposures since the camera has to be absolutely still while the shutter is open so I opted for a stepper motor right from the start. Keeping a cart stable on a monorail requires more engineering than with two rails but it can cut down on weight and makes it easier to mount to a single tripod with a screw hole in the centre of the rail. I didn't know how to build this so I went with two rails and wheels on either side to keep it stable.

At first I thought I can keep the cart lighter by mounting the stepper motor to the end of the rails. While this is true, once you add up the weight of the metal cart itself, a camera body and lens, and ball head, a single stepper motor wouldn't make much of a difference any more. Having the motor on the cart has several advantages: everything, from the camera to the motor to the control unit is in one place and you won't need to run cables all over the place; only half the length of timing belt is required since it won't loop around the ends. Here is a link to a good example of a DIY monorail motor-on-cart slider.

    Here is a quick test video I shot using the slider. Unfortunately, I bumped it a bit at towards the end but you get the idea. There will be more exciting timelapses in the future that actually use the motion/parallex effect in a meaningful way.

    Material List

    • Arduino: $5-20 depending on original vs clone and capabilities - it's easier if it fits a shield
    • Motor driver shield for Arduino: $20
    • Battery pack and switching regulator: $10
    • 12V NEMA-size stepper motor and mount $23 - alternatively a smaller stepper motor
    • Timing belt and pulleys $40 - one could probably find much cheaper spare parts somewhere else
    • Aluminium rails $10-20 - I can't remember exactly
    • Steel or aluminium cart and ball bearings - can't remember how much it was, maybe $20; I had the ball bearings already
    • Cheap, small to medium-sized ball head - don't use the really small ones like the Giottos Mini Ball Head if you have anything bigger than a compact point&shoot because it will wobble a lot and adjusting it will be very hard: $20-$30

    In the photo above - once you look past the rat nest of wires - you can see the motor driver shield sitting on the Arduino. All connections come out of the shield (they are fed through from the Arduino), so the rainbow ribbon cable is for the rotary encoder, there are some wires for the LED, ground and 5V, and also the stepper motor itself which is hooked up to the left-hand side 4-pin screw terminal. The two "things" encased in plastic in-line with the wires are a fuse and a switching regulator to bring the input voltage (9-12V) down to 5V for the Arduino. A linear regulator like the one that is on the Arduino would work too but might generate too much heat for a closed up enclosure.

    Photo above: a cheap but decent-sized ball head that unfortunately wobbles a little bit but does the job. Since all ball heads (and all decent tripods) use the same screw sizes, you can mount whatever you want, small and cheap or big and fancy. I like that the ball head has got a two-way water bubble level built-in.

    Programming

    On the Arduino platform I use the Adafruit_Motorshield library. To move the stepper motor the minimal distance and as smoothly as possible I run:

    Adafruit_MotorShield *motor_shield = new Adafruit_MotorShield();
    motor_shield->begin();
    Adafruit_StepperMotor *motor = motor_shield->getStepper(200, 250); // steps and speed
    motor->step(distance, FORWARD, MICROSTEP);

    I also set up an LCD and a rotary button using the SoftwareSerial and ClickEncoder libraries, respectively. Text can be written to the 16x2 LCD directly over the serial line, plus there are some special characters that move the cursor, clear the screen, and so on. The ClickEncoder uses up one of the timers of the Arduino and unfortunately it is the same used by the MotorShield library so I can't use both at the same time. This is ok because I only use the rotary encoder to set up all the timelapse parameters, and once the slider is moving and the camera is taking pictures I don't want to touch it again anyway. It's basically two separate programs: first the menu/settings, then the timelapse.

    Issues

    I found that the 200 steps per revolution that the stepper motor provides aren't quite enough for super smooth and slow motion, so after about 15-20 minutes with one frame every second the cart will already reach the end of the rails. It is possible that I haven't configured the motor correctly yet but it is set to micro-steps in the code and as far as I know this is the smallest possible rotation. I use micro-steps instead of normal steps because the provide smoother movement: a normal step would yank the cart and make the heavy camera wobble too much. It also makes sure that the motor is always enganged in case the rails are on an angle. This way the cart can't slide back down. To solve the problem of step sizes being too big I might incorporate some model kit plastic gears but for now I have avoided it since it isn't that easy to get everything lined up correctly without making the whole construction incredibly flimsy. There are also other stepper motors out there that provide twice or more the amount of steps per full revolution, usually through internal gears (see the alternative smaller motor I've listed above).

    Currently I'm running the whole setup off of 8 AA batteries, specifically Panasonic Eneloop AA Ni-MH Rechargeable Batteries(de). However, since the stepper motor requires 12V and 8 rechargeable AAs only provide a maximum of 9.6V, it does have issues climbing an incline stepper than about 20 degrees. On the flat it works great, though, and it lasts for many hours as well. In the future I might upgrade to a 12V battery or boost it up with a converter, maybe using a LiPo battery for their amazing energy density.

    Future Developments

    I've got a little micro-switch that I want to mount at the end of the rails so that it detects the cart hitting the end. This will eventually stop the timelapse. I also want to refine the menu system and hopefully improve the software side of driving the motors, i.e. better speed and step control.

    In case I've already exhausted all possibilities regarding the motors, I might actually have to add two differently-sized gears to the system to bring the speed down so that I can take hour-long timelapses with many hundreds of frames.

    And finally, panning while moving sideways would make my timelapses look much more impressive so adding a second motor is high up on the agenda. However, I'm not sure yet how to fit it between the camera and the top of the ball head (glue it to the quick-release plate?), or alternatively if it could or should live under the ball head in which case I'm worried about stability. The latter would see the motor mounted under the cart, however, which would be a very clean looking solution. Either mounting point will give very a different result when the rig is on an incline and depending on the subject it can work well or look really out of place.

    The most important improvement, however, to be made is getting it off the ground. At the moment grass or plants can easily get caught in the wheels and there are no points to screw in a tripod quick-release plate (the end trusses hook quite nicely into the top of my Manfrotto BeFree Travel Tripod(de) , though). Often something can look good at eye-level but having to put it all the way down on the ground limits my possibilities so a good 1/4" screw hole at either end would make it immensely more useful and stable in vegetation.

    Please head over to Google+ or Twitter @tobiaswulff (see links on top of the page) to discuss this article or any of my photography and videography work. My Flickr and Vimeo pages also provide some space to leave comments and keep up to date with my portfolio. Lastly, if you want to get updates on future blog posts, please subscribe to my RSS feed. I plan to publish a new article every Wednesday.

    Long-run timelapses across multiple seasons - Part 1

    Some links to products in this blog post are Amazon Affiliate links that earn me a few cents or dollars if a reader buys any product on Amazon through this link. The price of the product does not increase so it is a free way to support this site by using the links provided. The main product link goes to Amazon.com and the "(de)" leads to Amazon.de.

    This is the first part of a longer series of blog posts about timelapses. I have started planning for and taking long-run timelapses that span many weeks and months, and I want to talk about how these ideas and visions can be accomplished in a reasonably efficient workflow by an amateur photographer. I say "reasonably" because processing timelapses from RAW files and working on such long running sequences will always involve a lot of work.

    Who, and why

    Apart from an article on Photo Sentinel, there aren't many interesting articles or howtos available. I highly recommend reading the article if you're interested in timelapses because it showcases different techniques and links to some great videos in each category. However, it belongs to a company that sells specialised long-term timelapse equipment which does not really fit the kind of subjects I'm shooting. On Youtube and Vimeo there are only a couple of videos that portrait certain subjects in nature over the course of many months but there are some amazing and award-winning short videos and films that I will link to further down.

    The most impressive executions of this sort of timelapse - and the aforementioned howto talks about it as well - are several features by the BBC such as The British Year and of course Planet Earth. The team which shot the timelapses for The British Year talk at length about planning, shooting, editing and various tips in a blog post. I highly recommend Chad's blog and all the content on his website as it is a wealth of timelapse stories, workflow tips, and kit reviews.

    How-to

    The obvious but most time extensive way to shoot a timelapse across multiple seasons is to take individual photos of the same subject under similar lighting conditions and from the same spot over a long, long time. Another technique is to take multiple "normal" timelapses, that is sequence of an hour or a few hours, and then blend them together such as in the Youtube video "4 Seasons 1 Tree". Unfortunately, the blending will be very obvious, and there also isn't much movement or change within the individual sequences themselves. On the other hand, there is no flickering due to abrupt changes in lighting or weather. This could be enhanced by doing some masking and selective blending to change some areas of the image before others which can also be seen in the video as the ground changes before the tree does.

    The easiest way to accomplish a long running timelapse is to have a camera that can be left in a fixed spot and orientation. The photo above is actually a blend of two individual frames, one with different lighting and more leaves on the tree. It shows that blending and aligning photos on the computer can produce a very smooth result even if the original photos are totally unaligned and taken in completely different conditions. In amateur nature photography, it usually isn't an option to have an absolutely fixed camera spot because the locations are too exposed to the elements. Even in urban environments you wouldn't leave your camera or tripod anywhere except inside your own house or apartment - and then you wouldn't be able to take it somewhere else.

    Therefore - unfortunately - we have to re-set up the camera and point it at the same spot every single time. This gets very complicated if movement of the camera is involved but even with a static shooting position there will be slight variations due to uneven ground, zoom lens variations (zooms are not "clicked" after all) and inaccuracies when pointing the camera at the subject. A very sturdy tripod is important but because I usually travel on foot or bike and also take my equipment on hikes into the mountains, I couldn't just go for the most sturdy one out there. So my tripod is the Manfrotto BeFree Compact Aluminum Travel Tripod which I love because it fits even into a normal day pack, yet it can extend to eye level and is reasonable rigid. However, pushing down on it will bend the legs in their joints so it is tricky to get it set up 100% exactly the same way every time.

    So there will be variations in tripod position, tripod height, camera attitude and focal length. Luckily, those issues can be resolved almost completely in post-production and I will talk about methods and tools to align photos and blend them in the next blog post in this series. Apart from dedicated software and plugins for Lightroom there are also a bunch or free tools available that do a very good or even perfect job at the expense of a maybe not so polished user interface or some efficiency.

    Ongoing work and ongoing articles

    Something like the video "Fall" from NYC Central Park is probably the closest inspiration to what I am planning to achieve. I didn't know the video when I started my project. There is also a year-long timelapse from the Canadian Rocky Mountains which employs some really nice blending and obviously beautiful outdoor scenery.

    As I shoot individual frames and sequences for my own long-run timelapse video, I will add more parts to this series talking about specific shooting tips and releasing some more snippets of the ongoing work. Towards the end I'm sure it will all become fairly editing and video post-production heavy.

    Please head over to Google+ or Twitter @tobiaswulff (see links on top of the page) to discuss this article or any of my photography and videography work. My Flickr and Vimeo pages also provide some space to leave comments and keep up to date with my portfolio. Lastly, if you want to get updates on future blog posts, please subscribe to my RSS feed. I plan to publish a new article every Wednesday.