My Gopro 3+ Black 180 degree stereo rig

It's for stereo still photos, so no need for sync i guess.

Still depends on what you are trying to capture.
Scenes with lots of motion like someone juggling, then you need both the L&R to capture at the same time.
If there is moderate motion like the shadows changing as the sun moves, then definitely no.
Shooting constantly at 60 fps will still help with things like trees blowing in the wind or people walking by.

If you are creating full spherical stereo panoramas then
For still scenes you can put the camera in photo mode and do, shoot move shoot.
For motion scenes you will want to have the pair of cameras continuously rotate while shooting video.

Indeed, e.g. interior stereo stills would be able by shooting and rotating and shooting again.

There have been many >180 degree lenses discussed in this thread, but what would be the one to buy for a go pro (or clone) M12 lens as of April 2015?

"Gusev" wrote:
Indeed, e.g. interior stereo stills would be able by shooting and rotating and shooting again.

There have been many >180 degree lenses discussed in this thread, but what would be the one to buy for a go pro (or clone) M12 lens as of April 2015?

I am still using CCOM Tech 1.29 lenses from Aliexpress and I think that might be the best cheap easy to get option currently
http://www.aliexpress.com/item/1-29mm-1 ... 88585.html

CCOM Tech also make another "10 megapixel" fisheye
http://www.megapixellenses.com/sell-160 ... -lens.html
.. which would be excellent for some Gopro vr purposes but it is difficult (and more expensive than Aliexpress) to buy directly off them ... also it looks suspiciously like this Aliexpress "Focusafe" 1.58mm lens which is just rated at 2 megapixel
http://www.aliexpress.com/store/product ... 47172.html

They also make a new (I think) lens rated at 14 megapixels (!) -- 1.82mm 180 degrees -- "for VR" !
http://cctv-lenses.sell.everychina.com/ ... dv-vr.html
This would cover I think about 180 by 140 degrees on 4:3 W Gopro formats

Entapano's 220 degree lenses look great for side by side 3d Gopro movies and should be available for preorder tomorrow but maybe they will be in short supply. They have M12 and CS mounts (combined) so they should just screw in. They warn about secure mounting and precision alignment but I think the 220 is small enough for it not to be a big problem.
https://www.entapano.com/en/l/index.html

Izugar sells 194 degree lenses too but only including a 360 back to back mount -- but the sample images he has shown look very sharp and contrasty
http://www.izugar.com/product/z2x.html

btw .. I have a GearVR (Note4 version) now and 180 3d movies play great in MilkVR in that but I dont think you can upload that format to their hosting yet you but you can put them in a MilkVR folder on a MicroSD card and view them that way. S6 GearVR are meant to be faster and have a rectangular rather than the horrible Note4 circular view but they are not officially for sale yet. Visible resolution wise they are meant to be the same

"mediavr" wrote:

"Gusev" wrote:
Indeed, e.g. interior stereo stills would be able by shooting and rotating and shooting again.

There have been many >180 degree lenses discussed in this thread, but what would be the one to buy for a go pro (or clone) M12 lens as of April 2015?

I am still using CCOM Tech 1.29 lenses from Aliexpress and I think that might be the best cheap easy to get option currently
http://www.aliexpress.com/item/1-29mm-1 ... 88585.html

CCOM Tech also make another "10 megapixel" fisheye
http://www.megapixellenses.com/sell-160 ... -lens.html
.. which would be excellent for some Gopro vr purposes but it is difficult (and more expensive than Aliexpress) to buy directly off them ... also it looks suspiciously like this Aliexpress "Focusafe" 1.58mm lens which is just rated at 2 megapixel
http://www.aliexpress.com/store/product ... 47172.html

They also make a new (I think) lens rated at 14 megapixels (!) -- 1.82mm 180 degrees -- "for VR" !
http://cctv-lenses.sell.everychina.com/ ... dv-vr.html
This would cover I think about 180 by 140 degrees on 4:3 W Gopro formats

Entapano's 220 degree lenses look great for side by side 3d Gopro movies and should be available for preorder tomorrow but maybe they will be in short supply. They have M12 and CS mounts (combined) so they should just screw in. They warn about secure mounting and precision alignment but I think the 220 is small enough for it not to be a big problem.
https://www.entapano.com/en/l/index.html

Izugar sells 194 degree lenses too but only including a 360 back to back mount -- but the sample images he has shown look very sharp and contrasty
http://www.izugar.com/product/z2x.html

btw .. I have a GearVR (Note4 version) now and 180 3d movies play great in MilkVR in that but I dont think you can upload that format to their hosting yet you but you can put them in a MilkVR folder on a MicroSD card and view them that way. S6 GearVR are meant to be faster and have a rectangular rather than the horrible Note4 circular view but they are not officially for sale yet. Visible resolution wise they are meant to be the same

Thanks for the clear explanation mediavr. I will go for the CCOM Tech 1.29 lens.

Because I'm going to replace the stock lens for the CCOM Tech lens, does it even matter which China GoPro "clone" I choose? I've read some good things about the SJ4000.

"Gusev" wrote:
Because I'm going to replace the stock lens for the CCOM Tech lens, does it even matter which China GoPro "clone" I choose? I've read some good things about the SJ4000.

Find a tear down video to make sure the lens is not pertinently glued to the mount.

Here is my current workflow for 180 3d movies:

180 stereo -- rigs ...
Best panoramic stereo is often when there is depth from near to far. Near being say 0.5m. So this means for 3d 180 small cameras to get the interaxial down. I think 5cm is a good all round setting for an interaxial for this.

It is really important for sanity I think if your rigs can have an exactly repeatable layout. With Gopros this is hard with 3d printed rigs. And few 3d printed rigs are made for Dual Hero System rigs. Since Gopro3s Gopros have flat sides so it is easier now. My latest rigs are basically boxes where the cameras are pressed against opposite sides and corners of the box by a slightly wedge shaped block between them, and the cameras are pressed then hard against the back of the box.

Then you need to calibrate each camera carefully, individually,sitting in the 180 rig. Micro full circle fisheye lenses have a lot of manufacturing variance. Gopros have very loose standards for locating the sensor behind the lens barrel. (10s of pixels). It is almost impossible I think to calibrate this offset accurately without the image circle being visible in the frame -- so you can use the image circle cropping tool in PTGui.

I think it is better to have one camera as the master for calibration purposes. Calibrate this carefully with an indexed panorama head and PTGui. Have the camera mounted so that the No Parallax Point of the camera/lens is exactly over the rotation axis of the panorama head. The M12 full circle fisheyes on Gopros I have been using have been close to ideal fisheyes so if your distortion factors are not close to zero you might be doing something wrong. Once you have calibrated the master camera you need to calibrate the slave camera to it I think, rather than doing an independent NPP calibration for it. You need to tell PTGui that the lenses have different fov, a, b, c and h and v. You need to calibrate the slave to the master camera so that they are producing identical test images with distant scenery over the entire area of the fisheye coverage.

Now you can shoot 3d 180 videos and have a good starting point. I generally convert all the frames into aligned stereo pairs of equirectangular images (180 by 180) first using the parameters from the calibration process, using the Batch Builder and Batch Stitcher tools in PTGui.

Viewing these in a HMD you will see that you have good stereo in the middle of the frame but bad stereo in the frame corners especially if there are close features there -- so usually the bottom corners of the frame are the main problem. Because of the difference between capturing the stereo from a level view looking straight ahead and extracting oblique views from that, and the real world situation where you turn your head and tilt it down to view into the corners, you will need to warp the corners of at least one of the stereo pairs. Lately I think batching Puppet Warp in Photoshop or using Puppet Warp in After Effects is a simple way to do this. You need to drag the errant features in the slave image say up or down (vertical disparity is the main concern) after fixing the rest of the image with pins. If the slave camera is on the left, on the left bottom of the frame features will have to be dragged down some, on the right bottom of the frame features will have to be dragged up some. Stereophoto Maker (for anaglyph views) and LiveViewRift are my go to tools for doing the testing.


Posts: 179
Joined: Thu Apr 18, 2013 1:06 am

Tons of great info. Thank you for taking the time to document and share!

I have a couple of questions to clarify steps of the process. ( I'm using gopros with the 185° iZugar lenses)

Then you need to calibrate each camera carefully, individually,sitting in the 180 rig.

I'm assuming you mean this process (from PTGui site)

5.4. How can I calibrate my lens parameters?
For panoramic stitching you don't need to know the lens parameters since PTGui calibrates your lens automatically for each panorama. But knowing the lens parameters can be useful if you (for example) would like to correct a single image for barrel distortion. The lens parameters can be calibrated accurately as follows:

• Take enough images to build a 360 degree, single row panorama. Make sure the images overlap by at least 30%. Make sure that the camera is rotated around the 'no parallax point' of the lens, in order to avoid parallax errors.


• Load the images into PTGui, and execute step 2 (Align Images) of the Project Assistant.


• Switch to the Control Points tab and review all generated control points. Remove any misplaced control points, and any control points on moving objects (including clouds in the sky!). Also remove any control points on nearby objects, since these will suffer the most from any remaining parallax errors in your setup. Make sure that each pair of overlapping images has at least 4 control points (more is better). Ensure that there are some control points in the corners of the images as well, not just in the center.


• Optimize the project using the Optimize button in the Project Assistant.


• Open the Control Point table (Ctrl+B or Cmd+B). The control point distances should be small, generally less than 3. If you find control points with higher distances, correct or remove them by repeating the previous two steps.


• Switch to Advanced mode by pressing the Advanced button in the Project Assistant.

Now the optimized lens parameters can be found as the a, b and c parameters on the Lens Settings tab. Use the Lens Database button to save the values for later use.

Please note that different orientations (landscape vs. portrait) and different focal lengths (in case of zoom lenses) will result in different correction values, so be sure to save separate entries in the lens database for each zoom setting and for landscape and portrait orientation. Even at the same zoom setting and orientation subsequent calibrations may result in significantly different a/b/c values. This is normal, since completely different a/b/c values may represent very similar lens correction curves.

If, so can you clarify how to do this:

Once you have calibrated the master camera you need to calibrate the slave camera to it I think, rather than doing an independent NPP calibration for it. You need to tell PTGui that the lenses have different fov, a, b, c and h and v. You need to calibrate the slave to the master camera so that they are producing identical test images with distant scenery over the entire area of the fisheye coverage.

Finally, when you designate master camera and slave camera, do you do this so that when you modify the images (puppet-warp, etc.) you only modify the slave image so you aren't chasing distortion back and forth, or is there another reason for the designation?

Jeff

can you clarify how to do this:

Once you have calibrated the master camera you need to calibrate the slave camera to it,

In the calibration you shot videos and grabbed stills from the L and R cameras during the time the camera was in each position on the panorama head. Say the L camera was the one you were treating as the master -- just master in the sense of the camera that is rotating nodally -- it could be either depending where you had set the rotation axis -- under which lens. Then you know L cameras lens/camera parameters . Then after you are done in PTGui calibrating the L camera you delete all but the first frame of your 8 position (if the head is set to 45 degrees say) set of frame grabs and you add the first of the R camera frames. Then you tell PTGui that that the first and second images can have different fov, a, b, c, h , v and in the Optimize tab you set it to Optimize only fov, a, b, c, h, v of the second image.

Re warping you could warp either the L camera or R camera or both. It is more convenient mostly to just work on one. But working on both on the same area might be necessary to have more accurate control of the stereo impression.

I have done more with After Effects Puppet Warp lately and it is much more powerful than Photoshop in most ways for this. You have to imagine the image as a rubber sheet that you sticking pins in and dragging to different positions so strategic placement is necessary to get one part to move with other parts not moving in the wrong direction. But it is very powerful for introducing subtle depth impressions to depthless background areas as well as for fixing vertical disparities.

Here is a recent 180 3d movie where I used this warping to get better 3d in the corners and nadir:
https://www.reddit.com/r/oculus/comment ... 180_movie/

Btw if you are a Creative Cloud subscriber I see that the latest update for Premiere Pro supports audio syncing -- handy if you are not using Dual Hero System. Previously you would have needed Pluraleyes or video stitching programs for this.

Entapano's Entaniya super fisheyes are now for sale and they have added more sample images and some stitched panoramas
https://www.entapano.com/shop-en/

I tried stitching the 250 degree image pairs and they stitched fine and the geometry looked correct -- with PTGui settings approximately fov = 250, a=0, b=-0.06, c=0

An obvious disadvantage of the lenses for 360 twin camera 2D stitching like they are showing is that they are so large you would get a lot of parallax compared to more compact lenses with a dual camera rig (their entrance pupil is very forward of the camera body).

The 250 degree lens can be used to produce (in PTGui etc) a uncropped full circle fisheye 200 degrees in diameter from a full frame 4:3 Gopro image or video frame -- so great for dome use.

I like the specs and results of the 250 degree lens more than the other two for most purposes. The 280 degree lens is obviously better for directly up single camera 360 capture though. The 250 has the largest physical image diameter on the sensor (5.5mm) and so is using more of the sensor. The 220 lens has a distinct resolution fall off in the outer 20% of its image circle, compared with the other two, and the 280 has more purple flare than the other two in outer areas. The 280 has the smallest physical image diameter (4.2mm) .

All the lenses will image the other camera and lens in side by side stereo rigs unless the cameras are turned out from each other. I think you could turn out the 250 degree lenses (cameras) about 20 degrees to either side and still get straight ahead 180 by 180 full coverage on each camera (on 4:3 formats), but at the cost maybe of harder alignment in post. A big advantage of having large coverage generally for 180 3d is ability to do post image stabilization without running out of image. (I will write some more about faster workflows for stabilizing fisheye videos in After Effects soon.)