Wednesday, August 2, 2017

Twin NX1000 Image Processing

In this blog I will describe how I process my images from the twin NX1000 rig with the z-bar. Same concepts apply for all twin camera rigs in the z-configuration (the left camera is upside down).

There are three steps involved:

  1. Transfer: Transfer the images from the camera to the computer.
  2. Match: Make sure that the images are matched in pairs (needed for multicoversion)
  3. Process: Read the left image, read the right image, align, save, repeat. You can do this manually or use multicoversion where you go have a cup of coffee, read the paper, and come back when everything is done.

Sounds simple, but the devil is in the details. It is always in the details. One complicating factor is that the images from the left camera are upside down.

Let’s look at these three operations closely:

Transfer Images

This is a common operation when using twin cameras for stereo, but I have found that it confuses some people. The confusion comes from not understanding computers (specifically Windows and the concept of folders). But that's a topic for another day.

First, I have the SD cards clearly labeled R and L, so there is no confusion which is which:

I also have permanent folders in my computer for the R and L images. I download the R images in a folder clearly marked for the R images and the L images to a folder clearly marked for the L images.

Here is how Windows Explorer (Windows 7) shows the two folders, when placed side-by-side. As you can see, the images from the L camera are upside down (click at the picture to enlarge).

Match Images

When shooting with twin cameras, occasionally one camera fires while the other does not. This happens with the Samsung NX1000 cameras if one is turned on while the other is off, or one is turned off while the other is on. For one reason or another, there might be extra (non-matching) images. When this happens to me during shooting, I immediately delete the extra image. By following good turning on/off procedures (see: I do not get many “orphan” images. But I always check to make sure the images are matched, before I do multicoversion because if they are not matched, multiconversion will fail.

You could match images using Windows Explorer (look at the picture above, you can visually see if there are any extra images, and delete them), however I like to use StereoPhoto Maker’s “Open File List” which is very similar to Windows Explorer, only better.

Note: Some people use and recommend StereoPruner. This is a program by Cyclopital3D that can be downloaded here: This program sorts the right and left folders to match the images.

Personally, I prefer to use "Open Image File List". Even if you use StereoPruner, you should become familiar with this SPM function because it is very useful.

SPM – Open Image File List

Open StereoPhoto Maker (SPM) and under File, select “Open Image file list”. This opens a window that looks very similar to Windows Explorer. I navigate the folders to find the L folder. At the top select “Open another instance”. This opens a second window. I navigate to find the R folder. These steps are shown here:

When everything is said and done, I have two folders (from SPM) side by side, the left sitting on the right (on purpose, so I can cross-view the images). Here is what I see:

I scroll down (both SPM folders scroll at the same time, nice!) freeviewing the images. This allows me to detect any extra images, which I then delete. When I am done, I have matching R and L images and I am ready to process them. The entire operation takes a minute or two.

Before we move to the final step, I want to make you aware of two things.

Image Numbering & Renaming:

If you look at the pictures above, you will notice that the image numbering of the R and L files is totally different. For example, the first image in the L folder is SAM_9600, while the first image on the R folder is SAM_1337. These numbers are off by 8000+. I have done this on purpose.

If you format new SD cards and reset the image number, then the numbers from each camera will be matching. Eventually, with errors and orphan images, they will drift away but not by much. If the  image names overlap, then SPM will not do multi-conversion correctly. In this case, you will need to rename one group of images.

You can rename the entire group of images (usually the L images) with SPM. While on the Image File List, go to “Edit”, then “Select All Files,” then right click and select “Multi-Rename”. This is a powerful function that allows you to do interesting renaming in the entire group of images. As powerful as it is, I prefer not to use it.

With previous twin camera systems, I tried to keep the file numbers matching. That was a pain. Now, I follow a different strategy: I have them as different as possible. By keeping a totally different file numbering, I do not have to worry about renaming images.

How did I change the file name sequence? I reset the numbering in only one of the two cameras at some point and this gets the numbers totally out of sequence. You can reset the file numbers via the menu, as I mention in this blog:

Orientation Tag:

Notice that SPM shows the left image straight up but it has a number “3” in the corner. This number is called the “Orientation tag.” There are actually 8 different tags shown here:

By right-clicking at an image, you can select a different orientation tag. You can also select all the files (“Edit”, “Select All Files”) and change the tags on all of them (right click, “Set the Orientation….” (select what you like)).

Where does the orientation tag come from? It comes from the camera. If the camera knows that it is upside down, it marks the image with tag 3 “180 rotated”. Normally, all left images should have a tag of 3, but there is a situation where the camera does not know it is upside down. This happens when you point the camera up or down. In this case, the camera will give the file a standard “Original” tag because it is not aware it is upside down (think about this for a second…. when you point the camera directly up or down, there is no up or down camera). Because I shoot up and down often, I might select all files in the left folder and force the “3” tag before I try to match them. That’s just a detail, but it will eventually happen to you and you will wonder why an image from the L camera does not have the orientation tag “3” like the rest of the images. Now you know why.

Process Images

Processing the images can be done either manually (one at a time) or using multiconversion (batch processing, done by SPM).

For manual processing, go under “File,” “Open L/R Images,” find the left image, then find the right (the program prompts you). You then can do autoalignment (“Adjust”, “Auto Alignment” or press Alt-A). Save the combined and aligned image. If you move to the next image, SPM will automatically load the left image from the left folder and the right image from the right folder, because it is a clever program (so you do not need to navigate folders again).

Some people like to do manual processing like that. I prefer to do multicoversion. I don’t even attempt to view anything until everything has been aligned using multicoversion.

With multicoversion you go under “File” and “Multi Conversion,” and set up the dialog screen. You select “Independent (L/R)” as the Input file Type, tell the program where to find the R and L images, where (and how) to save the aligned image and anything else you want it to do. Here is how my multi conversion screen looks:

When I start multiconverion ("Covert All Files"), I always check the first image to make sure it is OK. If I see something wrong, I stop it, make corrections in the dialog screen and try again. You can check the aligned/saved images by opening another instance of SPM (you can run as many instances of the program as you like).

Everything sounds good. Except, when you load the image you just converted, you will notice that it is upside down!  It looks like this:

This is happening because SPM uses the name and orientation tag, from the L image to assign to the aligned image. Because the L image is upside down (orientation tag “3”) the resulting stereo pair will also have orientation tag “3”. To change this, after the alignment is completed, you can use SPM’s Image File List, select all the files and change the tag to “1”.

I have settled for a slightly different procedure: After I match the R and L images, I change the orientation tag of all L images to “1” (normal). Then, in the multiconverion screen, for the L image I select: “Rotation (180)”. The program then rotates the L image before alignment and the resulting image is not upside down because it carries the tag “1”. This is how my multiconverion screen looks (the only difference from the previous screen is the red square):

This completes my procedure. It is not very complicated and many steps are similar to when using any twin camera system. The only complication is that the left camera is upside down and it is the left image that SPM uses to give the aligned/saved image its name and orientation tag.

After a while, the processing steps become automatic. If anyone has any ideas or thinks they are doing this much easier or faster, I’d like to hear from you.

What’s in My Camera Bag II

In the previous blog ( I discussed the contents of my camera bag from 2009 (“Last Great Film Vacation”) to 2016. I also discussed the reasons why one stereo camera is not enough for me. I need a variety of stereo bases and close-focusing abilities. So my camera bag contained a standard stereo camera (Fuji W3 or Panasonic 3D1, which also allows for hyperstereos and close ups), a twin camera rig for mild hyperstereos, a single camera for single camera 3D, and a Panasonic camera with the 3D lens for macro pictures.

Things changed in 2016 when I discovered the twin Samsung NX1000 cameras (see:

Because of the normal spacing in the z-configuration (68mm) and good synchronization, this pair serves both as a normal stereo camera and also twin camera with a wider stereo base. It is also possible to use one camera for single camera stereo. This changed the contents and size of my camera bag, in a good way.

So, what am I carrying in my camera bag today?

The answer depends on the length, purpose and importance of the trip, vacation, outing, etc.  There are different levels:

  • Level 0: No stereo camera, just the phone for 2d pictures.

  • Level 1: Panasonic 3D1 camera. Even though this camera has a narrow lens spacing, it is easy to use, more compact than the Fuji and gives better pictures overall. If I only take one stereo camera with me, this is it.

  • Level 2: This is most often my “to go” camera bag. Here is a picture of it:

It consists of the following:

  • (Optional) Extra set of lenses. For general photography I use the 20mm (fixed focal length) lenses. I might carry other lenses, depending on what I plan to shoot. For example: 10mm (ultra wide), 16mm (wide), 45mm (shown here, for portraits or other pictures where a slightly longer focal length works better - if I carry a second pair of lenses, this is usually it). Any extra lenses are carried and stored as I describe in this blog:

  • Panasonic 3D1 camera (and platform to carry it better). Great for close-ups, one of my favorite type of pictures.

  • Small supplies: Pair of extra batteries, SD cards, cleaning tissue.

  • All that stuff fits inside the LowePro AW bag. I like this bag a lot because it fits the completely assembled NX1000 rig, without having to take the handle off. There is room in the main compartment for an extra pair of lenses. Small accessories (batteries, etc.) fit in a little pocket at the top. The 3D1 and flash fit in the front pocket. There are also two straps on each side that can hold one or two longer twin camera bars vertically, see:

  • Level 3: In addition to Level 2, I might carry equipment for specialized use such us remote/high perspective photography, wide base hyperstereo, macro 3d, bird/wildlife/zoo photography, underwater photography.

Macro pictures: I carry a Panasonic GX7 camera with the 3d lens. Possibly two lenses with 0.5mm and 1.0mm extensions. Possibly one or two more compact flashes, or the Chinese double flash. This requires its own separate camera bag. I am working on finding a similar system that works with the Samsung cameras so I do not have to carry the Panasonic. Then I will be able to take macro pictures with less equipment.

Extensive Flash: If I plan to do more flash photography, I might carry more flashes, slaves, or related equipment.

Hyperstereos: I can shoot hyperstereos (up to 8 inches) with the Samsung rig, or non-synchronized hyperstereos with one camera and shift. If I am planning to shoot synchronized hyperstereos with a longer base, I will take one or two camera bars (two bars can be connected to form a longer bar).

Remote shooting: I carry an extra remote cable. I might carry the remote cable anyway, in case I want to separate the cameras longer supported on a ledge or even hand-held by two different people. Here is combination that allows for this:

High Perspective: In addition to the remote cable, I carry a pole for high perspective shooting. Here is an example (our house, with no tree to climb on sight):

Telestereo: For this I need longer focal length lenses plus a twin bar and possibly a tripod. Here is a possible outfit, consisting of 50-200mm zoom lenses:

Underwater Stereo: I have used a water tight camera bag for the Panasonic 3D1 camera in the past, with good results. This is flat and easy to carry. There is no excuse not to have one with me all the times if I am close to water or if there is a danger of the camera getting wet. Here is an example:

Adjustable Z-Bar for twin NX1000 cameras

I have designed and been testing a new adjustable Z-bar for twin NX1000/NX1100 cameras. The idea is similar to the first one I made earlier (my first bar, see: with a bit more attention to the details. The big attraction of this bar is that the stereo base is adjustable.

My friend, Ted Whitten, encouraged me to build this. At first, I was resisting, being very happy with the Werner body mount ( But then, something happened: I was ready to photograph the Memorial Day Parade in Brecksville. I had my cameras mounted side-by-side on my twin camera bar. I was standing under an electrical wooden pole. I looked up and saw the American flag, among transformers and electrical wires. The flag was being lit by the sun and everything looked just right. I wanted to lift my camera and take a picture of the pole and flag, but I could not, because I did not have a normal stereo camera. Using the side-by-side cameras would not have worked because I was too close to the subject. I needed normal camera/lens spacing. But I did not want to disturb my setting (it takes time to switch from side-by-side to the body mount), with the parade starting soon.

At that moment, I wished I had a z-bar with adjustable stereo base. So, I decided to build one. While Ted was visiting, we worked on a pair of bars. I figured out the basic dimensions and made two bars, one for Ted and one for myself. I tested my bar and it works fine. Now Ι got to the point where that’s all I use. So, I decided to start making this bar available for others.

Here is how I make the bar

I start with a piece of aluminum channel, 3" (tall) x 1" (wide) x 0.125" (3mm, thick). This material was recommended to me by Bob Karambelas, as described in the previous blog. It is the same piece I used for my first mount, and Bob for his, before we knew about the body mount.

I buy the aluminum channel in 24" pieces, and then cut it as shown in this diagram:

I cut a piece about 9 inches (230mm) long. I decided on this size because this is the length of two cameras touching each other. This way the bar will not spill out of the cameras when they are at their closest point.

I then remove two pieces, based on two important dimensions: 1) The center column is 20-22mm (I started with 20mm, now I favor 22mm). This column is in the back and does not cover the screen when the cameras are touching each other. It serves for both structural strength and camera alignment (when the cameras are close enough).  2) I leave a “step” of 8mm high. This is the step that the cameras rest on, and it helps to align them. This is tall enough to help align the cameras, but not too tall to hinder the two lower buttons or the screen.

After removing these two pieces, I need to drill holes and a channel at the top and bottom arms. I drill a hole 34mm from the center line and 15mm from the back step. These dimensions are dictated by the location of the camera tripod socket. My first design only had this hole and the cameras were at a fixed minimum spacing (touching each other). For this new adjustable design, I create a channel about 65mm long as shown in the schematic.

There is only one important detail left:  The distance from the top to the bottom is 76mm (total height of the channel) – 2x3mm (thickness of each arm) = 70mm. The distance from the bottom of the camera to the center of the lens is 33mm. So each camera must be raised by 2mm for the lenses to be aligned: 33mm + 2mm = 35mm, right at the center of the 70mm z-bar spacing.

To raise each camera by 2mm, I use a rubber washer for each camera. This is 2mm thick so it raises the camera, plus it holds the screw in place when the cameras are removed. The only issue with the rubber washer is that it hits the bar and the cameras do not slide smoothly. Also, it could be contributing to some misalignment. I am now experimenting with a piece of plastic. Check later for updates on this.

Update: I tried a piece of hard plastic and the cameras slide smoothly and the alignment is maintained (the rubber was being compressed, the hard plastic is not). It is a piece 20x60mm, with a hole drilled. It keeps the screws in place, raises the cameras, maintains good alignment. That's the way to go now.

The final product, with cameras mounted, looks like this:

(Note: This is my first bar… The back column is not straight. I am trying to do a better job since then )

Regarding the tripod sockets, there is one at the top and one at the bottom. I positioned these a bit off center so any screw thread from a tripod or camera grip does not hit one camera. At first, the z-bar was totally symmetric so either side could be the top or bottom. In my last batch I left one mount screw standard 1/4", but made the other one 3/8" for two reasons: 1) In case one needs a 3/8" mounting socket. 2) I added a 3/8 to 1/4 inch adapter. The adapter is made out of stainless steel so it is more durable than the easily deformed aluminum. I recommend using this side as the bottom.

Advantages of the Adjustable Z-bar

Compared to the body mount, this z-bar has two advantages:

  • Adjustable stereo base: This is a big one. One way to think about the stereo base is in multiples of the standard stereo base, which is around 65mm or 2 ½ inches. Let’s call this SB (Standard Base). The body mount only has one stereo base, SB. This z-bar goes up to 3xSB (about 8 inches or 200mm). 

Here is a quick way to get three different stereo bases, in case you like to bracket stereo bases:
  • With cameras touching: 1x SB
  • With one camera extended: 2x SB
  • With both cameras extended: 3x SB

  • The cameras can be removed from the mount very easily (unscrew the screws by hand). There is no need to take off the lenses and no tools are required.

Some other points:
  • Any shoe-mounted flash will work since there is no mount to interfere over the R camera.
  • The batteries and memory card can be accessed by simply sliding each camera out (see picture below).
  • There are plenty of standard 1/4" mounting sockets. One at the top, one at the bottom, plus the two screws that hold the cameras have a socket at the bottom. 
  • Finally, the 8 inches total stereo base of this rig is the same as my 12 inch twin camera bar. So, this z-bar simplifies things. Not only I do not need to carry the 12 inch bar, I also get all my stereo pairs in similar format, which simplifies processing.

Disadvantages of the Adjustable Z-Bar

  • It is not as well-aligned as the body mount. When the cameras are touching, alignment is good enough. When they are separated, alignment gets worse. I am working on this and will report back later, after I try other ways to raise the cameras by 2mm. This misalignment is not a practical problem for me because StereoPhoto Maker aligns the images very well.

  • It does not look as elegant as the body mount. I am still learning how to machine these. I am now working at making smoother curves, but these bars do not look nearly as elegant as the bars I have from Co Ekeren. But, they work.

One last note: The standard one-piece remote cable, is not long enough for this bar. I have ordered a set of longer cables that will work. But I have found advantages in using the twin remote: The main one is that you do not have to touch the cameras, so pictures with slower shutter speeds can potentially be sharper. 

My standard configuration for these cameras now is this adjustable bar, plus the twin remote.  Plus my favorite camera grip. This is how my rig looks right now (with 20mm lenses):