Manually Shooting a Six Panel Pano Shooting Straight Down

[MRomine]

If you wanted to stitch together a six panel pano shooting straight down, how would you go about doing it? M2P.

I have a request from a client who wants an aerial shot of a construction site looking straight down onto the property. But because I am in a Class D airspace near the local airport I can only fly to an elevation of 100'. But at one hundred feet I can only get about 1/6 of the project into a single frame. So I was thinking about trying to stitch together six frames but I have no idea of how to go about lining up the drone and over lapping each frame by 30% so that either LR or PS can stitch them together.

Your thoughts?

 

[Not A Speck Of Cereal]

Haven't done this, but off the top of my head:

Panos are done from a single, stationary point. if you're thinking of moving the drone's position for each image (so it is directly above each of the 6 positions), the stitching would go poorly.

There is a vertical pano mode, but it is a little up, straight, a little down. It's nothing like what you want (or at least, only about 1/2).

So manually, I would do the first 3 (0 degrees, about 37.5, and 75 degrees), then turn the craft 180 degrees around for the next 3 (reverse order of degrees from above).

Maybe the degrees wouldn't go all the way to 0 for your needs (you might not need to be square with the horizon on each end to capture the whole construction site) -- that would be up to you to figure out / experiment with.

One of the two sets of 3 would need to be rotated 180 degrees before stitching.

And the stitching would be all image tops and bottoms (no images stitched at the sides, which is the more typical kind with horizontal panos).

Eh?

Let me know if I wasn't clear.

 

[brett8883]

If you wanted to stitch together a six panel pano shooting straight down, how would you go about doing it? M2P.

I have a request from a client who wants an aerial shot of a construction site looking straight down onto the property. But because I am in a Class D airspace near the local airport I can only fly to an elevation of 100'. But at one hundred feet I can only get about 1/6 of the project into a single frame. So I was thinking about trying to stitch together six frames but I have no idea of how to go about lining up the drone and over lapping each frame by 30% so that either LR or PS can stitch them together.

Your thoughts?

We do this all the time with mapping. You can use something like drone deploy, Litchi, or Pix4Dcapture to set up the flight. Then just stich in photoshop like normal. It’s much easier for photoshop to stitch photos where the camera has moved to take the photos since there is no perspective distortion.

You could do this manually but the trick is you need a good 40% overlap on all photos.

 

[Meta4]

If you are stitching it yourself, you should use a planar projection.

 

[Paul2660]

Center your drone, turn on the grid on the screen. You should be able to visually stitch the image by moving the gimbal only. Do no move the drone or you will change the perspective and the image will never stitch together. I would start with the gimbal straight down, then manually move it upwards to the top, using the grid lines as a guide to the overlap.

You have a pretty wide angle lens, and the drone has a built in vertical pano mode only uses 3 image however that those three images will cover a huge amount of territory.

Also remember that as you angle the gimbal down, distortion will really kick in and object will start to push out towards the edges (you see the effect with trees all the time) and as you aim up the horizon will start to curve, (edges will angle up). and as you look down edges of horizon will angle down.

I would consider using Photoshop CC or LR for a quick construction or PTgui for a tool with more control.

Paul C

 

[brett8883]

If you are stitching it yourself, you should use a planar projection.

@Meta4 and I agree on something! In LR PS or camera raw the flat projection is called “Perspective” and it’s meant to have the camera move between shots so ignore advice about not moving the camera. I do shots like this everyday.

 

[Meta4]

Center your drone, turn on the grid on the screen. You should be able to visually stitch the image by moving the gimbal only. Do no move the drone or you will change the perspective and the image will never stitch together. I would start with the gimbal straight down, then manually move it upwards to the top, using the grid lines as a guide to the overlap.

That's definitely not the way to do it and moving the drone won't prevent proper stitching.
Here is a part of a composite image of a 30 acre site.
The full image was created by stitching 300 individual images (with big overlaps), collected by flying the drone all over the site in a grid pattern,looking straight down.

 

[Paul2660]

I stand corrected.

I was not clear in my first post.

If you pan across a scene for a pano by moving the drone across the scene the objects in the background will not align with the foreground. Nothing will stitch it correctly. This is for a horizontal pan working across a scene. Take 4 horizontal images across a subject.

If you keep the drone in the same position and pan the camera by yawing the drone across the scene the pano will align just fine. Again taking 4 horizontal images. The drone stays in one position but is rotated across the scene.

That is what I am talking

The 360 images are taken with the drone moving around a circle. The drone still stays in the same location relative to the scene

Paul C

 

[brett8883]

I stand corrected.

I was not clear in my first post.

If you pan across a scene for a pano by moving the drone across the scene the objects in the background will not align with the foreground. Nothing will stitch it correctly. This is for a horizontal pan working across a scene. Take 4 horizontal images across a subject.

If you keep the drone in the same position and pan the camera by yawing the drone across the scene the pano will align just fine. Again taking 4 horizontal images. The drone stays in one position but is rotated across the scene.

That is what I am talking

The 360 images are taken with the drone moving around a circle. The drone still stays in the same location relative to the scene

Paul C

Paul,

That’s still not correct. Take any photo and cut it up into 6 pieces. Now if you were to have taken those 6 pieces as individual shots by moving closer to the subject and and moving the camera across a grid pattern the resulting photo would look just like the original.

The perspective does not change because the viewing angle does not change only the scale.

 

[Paul2660]

If that works for you that’s more than I can explain

Doesn’t for me. Tried it many times.

I have never been able to slide across a scene horizontal with a drone and have the images align. I have to stay fixed in one spot and yaw the drone across the scene. Just like taking a pano with a camera on a tripod with panning head. My typical pano is 6 shots each a 5 shot bracket. 3 low yawing across the scene then 3 up yawing back the way I came using the grid lines for alignment.

Only way I know to slide across is use a tech camera or shift lens which drones can’t do.

Paul C

 

[brett8883]

If that works for you that’s great.

Doesn’t for me. Tried it many times.

I have never been able to slide across a scene horizontal with a drone and have the images align. I have to stay fixed in one spot and yaw across the scene. Just like taking a pano with a camera on a tripod with panning head

Only way I know to slide across is use a tech camera or shift lens which drones can’t do.

Paul C

Paul we must be talking about different things. I know you are very knowledgeable.

Here are 9 photos it took of a property I did a survey on. These are 9 photos out of several hundred taken but you'll get the idea.

I could not have fit the entire building and parking lot into the frame with just one photo at this height. All 9 photos were taken with the gimbal at the same angle to the ground(it was not straight down) and only the drone moves locations and not heading.




Here is the same 9 photos merged in Light Room using the "Perspective" projection. You folks at home can try this yourself with my photos and you'll get the same result. I also enabled auto crop so it would crop the photos for me as I didn't take these in perfect straight lines.


Had to down sample so it would be uploaded to the forum.

 

[Meta4]

If that works for you that’s more than I can explain
Doesn’t for me. Tried it many times.
I have never been able to slide across a scene horizontal with a drone and have the images align.

It's quite simple and there's a whole industry based on it, using drones for survey and mapping.
Here's a screenshot of an app flying my drone and shooting the images as it follows a preplanned grid pattern across the site:

Here's the pattern of the shots taken:

And here's a very much reduced version of the final huge image created from 300 individual images:

I have to stay fixed in one spot and yaw the drone across the scene. Just like taking a pano with a camera on a tripod with panning head. My typical pano is 6 shots each a 5 shot bracket. 3 low yawing across the scene then 3 up yawing back the way I came using the grid lines for alignment.

By moving the camera across the site looking downward, every image is taken from the same distance.
If you stay in one place and rotate the camera, some elements will be close to the camera and others will be off in the distance.

 

[Paul2660]

I understand that looking down it works ie mapping. And the previous post shows it clearly. And Thanks Meta4 for your example.

I don’t map. So have never shot straight down and moved across the ground but will try it. Don’t use apps for mapping so that’s out of my ballpark. Just use panning to get more overall resolution for a particular scene to print.

What I was referring to is with the camera up in the normal straight ahead position. Then moving across a scene with the drone. I have tried this multiple times and the perspective changes between the background and foreground as you move across. Image can’t stitch. Tried this multiple time moving along a railroad bridge horizontally. The scene would not stitch because the background changed relative to the foreground. No matter what solution I used in LR or Ptgui.

Paul C

 

[brett8883]

I understand that looking down it works ie mapping. And the previous post shows it clearly. And Thanks Meta4 for your example.

I don’t map. So have never shot straight down and moved across the ground but will try it. Don’t use apps for mapping so that’s out of my ballpark. Just use panning to get more overall resolution for a particular scene to print.

What I was referring to is with the camera up in the normal straight ahead position. Then moving across a scene with the drone. I have tried this multiple times and the perspective changes between the background and foreground as you move across. Image can’t stitch. Tried this multiple time moving along a railroad bridge horizontally. The scene would not stitch because the background changed relative to the foreground. No matter what solution I used in LR or Ptgui.

Paul C

The same concept will work Paul. The keys are you have to have enough overlap, use “perspective” projection in PS LR, have lots of overlap and finally...

you must shoot the photos in order(“Perspective” projection in LR PS uses the first photo as the “master” photo and then stitches the next photo to the first photo and so on. If you have two photos next to each other that do not overlap then this won’t work. My photos above have 60% overlap.

If you are doing a multi level pano you must have the last photo in a row overlapping the first photo in the next row. So to do a 3x2 pano you’d have to go across left to right for the first row and then right to left for the second row. The photos on each row must overlap with the photo above it and the photos next to it.

 

[Deleted member 94047]

If you are doing a multi level pano you must have the last photo in a row overlapping the first photo in the next row. So to do a 3x2 pano you’d have to go across left to right for the first row and then right to left for the second row. The photos on each row must overlap with the photo above it and the photos next to it.

Thanks for this Brett, but isn't this near impossible to do while manually flying? Is there a way to do this with Litchi?
Thanks!

 

[Meta4]

Thanks for this Brett, but isn't this near impossible to do while manually flying? Is there a way to do this with Litchi?

The order of shooting doesn't matter with specialised stitching programs.
One of the mapping apps (Pic4D maybe?) has a feature to map vertical surfaces like the facade of a building etc.

I have tried this multiple times and the perspective changes between the background and foreground as you move across. Image can’t stitch. Tried this multiple time moving along a railroad bridge horizontally. The scene would not stitch because the background changed relative to the foreground. No matter what solution I used in LR or Ptgui.

The process should work just the same but if you have elements much closer to the camera than the main image, the difference from one shot to the next will be too great for stitching.

 

[brett8883]

Thanks for this Brett, but isn't this near impossible to do while manually flying? Is there a way to do this with Litchi?
Thanks!

Its difficult but not impossible. The overlaps don’t have to be exactly the same. Error on the side of too much overlap.

The order of shooting doesn't matter with specialised stitching programs.

Correct but in PS LR it does matter.

 

[Photoman482]

That's definitely not the way to do it and moving the drone won't prevent proper stitching.
Here is a part of a composite image of a 30 acre site.
The full image was created by stitching 300 individual images (with big overlaps), collected by flying the drone all over the site in a grid pattern,looking straight down.

Can I ask what mapping app you used for this?

 

[Deleted member 94047]

Its difficult but not impossible. The overlaps don’t have to be exactly the same. Error on the side of too much overlap.

Using the onscreen grid line as a guide, do you think an overlap of 1/3 between the consecutive pictures in the first raw; and then an overlap of 1/3 between rows and columns in the next raw (s) would be enough? That would make shooting a little easier. For a 3X2 pano for example, this overlapping by a third technique will give us 6 pictures with overlaps like this (excuse the crude drawing; numbers designate sequence of shooting, shaded areas represent overlapping areas between pictures)

 

[DonF01]

I watched a mapping consultant do this with a phantom 4 of a railway yard and they set up targets on the ground that were used to align the drone and allow dimensioning of objects in the image afterward.