Archive for the ‘Video’ Category

A Return to Stereograms

4 April 2018

I have mentioned working on stereograms previously. These last couple of weeks have seen me focused on them.

Stereogram created from drone video taken at Wickahoney. See text for details.

Most that I have done before are close-ups, if you will, or portrait oriented.

I wanted to play with stereograms some more, this time focusing on landscapes. My goals were, first, to get them working consistently and second to hopefully work out any rules unique to stereograms.

In my mind’s eye, I remember sitting on the floor at my grandparent’s with a big box of stereograms and a now antique viewer. I would pick out a card with it’s two slides, read the caption, drop it in the holder, and clap the stereoscope to my face. I remember being fascinated how I could see a 3D version of a scene and how it contrasted from the pictures on the wall.

More, I remember most of them were landscapes.

Now, I’ll grant you my memories of those images are likely rose colored by time and they may not have been as fantastically 3D as I seem to remember. Most indubitably, though, there were hundreds of landscapes and not so many of flowers, people, or objects.

My goal in this recent project was to create valid 3D landscape stereograms. I also needed to work out what the limitations were, and how best to create a pleasing image that was also 3D.

Like this one:

One of the spots that overlooks Swan Falls and the Snake River Canyon, looking downstream from the dam.

Or this one, where the red rock formation just pops out at you:

Looking at Swan Falls Dam and the Snake River Canyon. The red rock is very prominent in the foreground.

What are the rules?

Aside from standard landscape photography composition “rules” I felt there must be some additional guidelines that would drive the composition.

As it turns out, there are, and there aren’t.

One of the things that you need to keep in mind when creating stereograms is:

  1. Take a picture of your subject. Remember where the center of your picture is on the subject.
  2. Take a step to the left. I usually stand with my feet just more than shoulder width apart. After taking the first picture, I move my right foot to touch my left foot then move the left foot so I am again standing with feet apart.
  3. Aim the camera at the exact same point on the subject as before.
  4. Take another picture.

That is my way of getting paired, handheld pictures. The first picture taken thus becomes the “right” picture (as in taken from the right) and the second becomes the “left” picture. The key to assembling the stereogram is the right picture goes on the left side and the left picture goes on the right side.

You can, of course, do it stepping to the left instead. In this case the first image becomes the left picture and the second becomes the right picture. No biggie, just get into the habit of doing it the same way each time.

There’s times a question arises whether or not the middle and far parts of the photograph actually show as 3D. Sometimes they do, sometimes they don’t. Sometimes they work if you have some decent foreground detail, other times you don’t need that foreground to make it work.

Willow Creek, off Black’s Creek Road. Notice the apparent differences in 3D impact in this compared to the Swan Falls stereograms.

And then, there’s the issue of anything that’s moving…that’s likely to produce “ghosts”, faint or translucent objects in the photo. Your main scene, the one you want to see in 3D, has to be still. Trees moving in the wind, clouds passing by overhead, cars on the road, people moving…all those and more need to be avoided.

One way to avoid natural movements such as clouds and water ripples is to use a long exposure time. That way, things get “smudged” smooth. Ripples on water, for example, become a soft flat surface and clouds become featureless.

Interestingly enough, I have one stereogram (below) where the two angles are such that one shows the parked truck and the other doesn’t, and yet the truck is solid in the stereogram view. It’s not a translucent ghost due to being in only one of the paired images. Yet another stereogram I’ve done freezes a car in one picture but it’s not in the other and this time it shows as a ghost car. Go figure. That’s what I mean about “there are and there aren’t additional guidelines.” More likely I haven’t figured them out yet.

Notice how the black truck is in one image but not the other, yet still comes through in the stereogram as solid, not as a ghost image.

By the way, the Wickahoney stereograms were all pulled from a video created by orbiting my DJI Phantom 4 around the midpoint of the ruins. You do remember that a video is merely a string of still images played back rapidly? Each pair, in this case, were pulled from about 1 second apart, e.g. one would be from 13 seconds into the video, and the second of the pair would be from 14 seconds into the video. When doing this, creating a stereogram from a video, you want to be sure the video still image isn’t blurry due to the drone moving too fast, to continue this example.

Stereogram from Wickahoney drone video.

One thing I did discover is that if you use a zoom or telephoto lens to enlarge something in the distance and make it part of your foreground or the middle distance in the photograph, you have to displace the camera location much more than a single step to one side. A problem I encountered was I could properly displace the distant solitary tree but the mountains behind it shifted significantly. They shifted enough that even though I could get the tree to be reasonably 3D, the more distant mountains were blurry.

A wide angle lens, though, works great and lets you really bring in some foreground:

Snake River Canyon from an overlook at Swan Falls, looking upriver from the dam.

And that’s as far as I’ve got. I’ll be going out and shooting more landscapes, as well as some closer subjects.

I think I know how to apply this technique to video as well and plan to try it with the video used to make the above Wickahoney stereograms. That’s for another time, though.

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OK maybe not quite back yet

20 March 2017

Like it says, maybe I’m not yet back into the writing grind. Still, some life is better than none, eh?

Since that last post, I’ve been mostly working on my ham shack. I now have a laptop set up for use with my radios and the setup works either on the desk in the house or in the vehicle up in the hills. Simple plug and play. Plus I got my radio desk cleaned off, finally!

I designed and built a switchbox that effectively gives me a Tigertronics USB SignaLink with two different radio jumper setups. It’s a simple circuit, just bringing the SignaLink JP1 socket out of the SignaLink enclosure and creating two parallel sockets in the switchbox instead. With a jumper block in each, I can easily switch the SignaLink between the two radios by flipping switches instead of having to open the SignaLink enclosure, swap jumper blocks, reassemble the SignaLink, and switch radio cables. A 15 minute operation is now down to 15 seconds. Nice trade, if I do say so myself.

You can see this switchbox in the picture right under the SignaLink.

The ham shack today. The new switchbox is under the SignaLink between the two radios, above the laptop.

Yup, those of you that are interested, it switches between the Kenwood TS-130V on the right and the Yaesu FT-2500M on the left. Being deaf, my focus is on the digital modes and a friend who is 20 miles away and I plan to play with the digital modes on 2m. So, I expect to be switching back and forth: experimenting, playing, and chatting with my friend on 2m and doing the same on HF with whomever’s out there. The 2m setup will allow us to both get familiar with various digital modes, including CW, and get in some regular practice with them regardless of HF band conditions.

I’ve finally been able to make the test videos for my video project. I have sure learned a lot just making these two 2 and 3 minute videos. Not only post processing, but things that have to be watched out for when filming. Trust me, I’m getting a new respect for directors and filmmakers.

The GoPro has definite fisheye artifacts, as I mentioned previously. I’m still feeling my way in the editing room dealing with this, but I think progress is going well. The Phantom 4 video doesn’t need much editing, as far as colors, etc., but I do need way more practice flying. I discovered that among other things, mimicking a bird taking off isn’t quite as simple as “just push the two control sticks at the same time.” Yeah, there’s that, but you don’t push them the same amount. I also absolutely must fly the planned route ahead of time or I’m going to have very definite un-bird-like behavior.  Even so, everything looks to be saying the video I want to make is doable.

Other than that, I’ve mostly been doing reading, studying Blender, and at least thinking about writing more Pa’adhe stories. Oh, and I have some more mead brewing.