Messages

1

General / Re: objects in Inspire Pro model are vertically slanted

« on: November 23, 2016, 05:59:32 PM »

I wonder what the rolling shutter speed is on the a6000 because we were getting excellent models at 4 m/s.

Are you taking stills from video? The a6000 doesn't have rolling shutter for still images, it's a mechanical shutter.

2

General / Re: What is the best camera between these two ?

« on: September 30, 2016, 05:08:05 PM »

Doubt it will make much difference. From an aerial platform 8mm is too little difference in focal length to significantly impact how high you'd have to fly. It's the same sensor, so if I were you I'd give more consideration to the size/weight of the airframe and potential increase of portability with the Mavic.

3

General / Re: DJI Phantom 4 for 3D mapping

« on: August 08, 2016, 04:52:59 PM »

I assume the sensors you're mentioning are the sonar and the camera to help it stay in position? These sensors will not have an impact in the images taken. Which, regardless of everything else, need to be crisp photos.

The sensors are actually 2 depth-sensing cameras, as I understand it, used to detect distance to objects (i.e. the ground, rooftop for below, or a tree, for the front-facing ones).

In short, to answer your question - the Phantom 4 works much better for photo-modeling than does, for example, a Phantom 2 with a GoPro or the vision camera (both fisheye lenses). The Phantom 4 camera is "wide" but not fisheye. I've never used a Phantom 3, so I can't speak to that.

4

General / Re: FF camera questions: a7Rii vs. D750/810

« on: March 30, 2016, 06:49:08 PM »

I read that the Mark 2 a7r has built-in mechanical image stabilisation. I'm not sure if this can be turned off or not but as far as I know image stabilisation ruins it for photogrammetry purposes.

Maybe only if you are worried about extreme accuracy... I'm not particularly worried about accuracy down to the sub-centimeter level, but rather worried about being able to take blur/noise-free handheld images in dim light. Should have specified that in the original post.

5

General / FF camera questions: a7Rii vs. D750/810

« on: March 29, 2016, 07:24:59 PM »

I've been using a Nikon D810 for photo-modeling for work for the past few years (and before that a D600). I've decided I'd like to replace my Nikon D90 and Sony NEX-5, great as they are, with a new full-frame camera. The D810 gets incredible results due to its ISO performance and high MP count.

I've really like how small and light the mirrorless NEX-5 is, and while I know the A7Rii will be quite a bit heavier, it's nowhere near as cumbersome as the D810. Hefting one of those around 8 hrs per day taking photos nonstop takes a toll on ones arms.

Does anyone have experience comparing the A7Rii and the D810? The new Sonys are supposed to have great ISO and dynamic range performance... I don't really have any existing lenses that would sway me one way or the other, I'd just like to get something that's as good as possible for photo-scanning.

6

General / Re: How to take photos

« on: December 20, 2015, 10:19:11 PM »

Just because the output you get looks good doesn't mean it is good nor does it mean it's as good as it can be.
From a theoretical standpoint on photogrammetry a fixed focal length and preferably a fixed aperture parameter is always better.

That goes without saying. The amount of care and meticulousness you take in capture is in direct relation to what you intend to use the end result for.  Hope to take millimeter-accurate measurements from the model? Then of course you'd better be as absolutely careful in shooting as possible. Just want a quick and dirty digitization of something? Shoot with your cell phone.  I suspect most people are aiming somewhere in between, and that's the group my comment was aimed at.

7

General / Re: How to take photos

« on: December 18, 2015, 07:26:43 AM »

B: Agisoft doesn't mind focussing.....you can shoot up close at point blank range for a detail and from 20 meters away for a overview of the same building AS LONG AS YOU KEEP YOUR FOCAL LENGTH FIXED, that is from experience and that stands.

I often change focal lengths and combine photos from different lens and the results come out fine without any trouble aligning, so I would say to worry more about making sure the photos are technically good (proper exposure, in focus, etc..) before worrying about focal length.

8

General / Re: Drone Custom Camera Specs

« on: December 05, 2015, 04:50:44 PM »

What's wrong with any of the thousands of existing cameras? Just strap one to a drone. There's no such thing as a "drone cam"... that's just a camera that has been put on a drone, which you can do with nearly any camera, provided you have a drone big enough.

The most important thing for a camera that has been put on a drone is the ability to downstream a live view, if you need it, or to have an intervalometer. Glass quality, MP count, etc... don't really matter because that's all been figured out already by the camera makers: obviously you'd want the best of everything if we're talking an ideal scenario.

9

General / Re: Aerial photography overlap overspecified? What works?

« on: October 02, 2015, 09:54:07 PM »

Do more flights if you can't get everything in one go.

10

General / Re: 3D Mesh With textures from PhotoScan to "Unity 3d / UNREAL" Game Engine for iOS

« on: September 23, 2015, 04:24:21 PM »

Cool idea, using the annotations to walk through the climb.

11

General / Re: build a good texture

« on: May 14, 2015, 05:50:34 PM »

They were not good so I deleted the sources.

well maybe that's why the texture wasn't any good....?
PS isn't magic, it can only work with what you give it.  If the photos are blurry, dark, overexposed, etc that will all affect different parts of the alignment and texturing process.

12

General / Re: build a good texture

« on: May 12, 2015, 09:21:25 PM »

Hi,
From your texture it looks like you have a lot of 'shine' or specular reflections in your source images.
It's also being compounded by ISO you are using try sticking to 100.
Reducing your spec is your first priority if you don't want to just fix it in post. Look into polarization.
You will get areas in the texture that will be more blurry compared to others even if you have perfect pictures.
What i usually do is generate a large image and reduce down.
hope this helps

I highly doubt that ISO 100 vs. 400 is the reason for the artifacts in the texture.  It's more likely simply a result of photoscan trying to blend a high number of photos together.

13

General / Re: Photoscan giving me (two) different alignment point clouds (Bug?)

« on: May 12, 2015, 09:15:57 PM »

You need to use the "flip-v" button on the texture in ZBrush.  Textures come into ZBrush upside down by default.  Same when you export a texture FROM zbrush - you need to flip-v it.

14

General / Re: New Drone from DJI- Inspire

« on: April 29, 2015, 09:18:21 PM »

... and then came the Phantom 3 ...
https://www.youtube.com/watch?v=7jJn7uvqgc0

I find the Phantom 3 to be really underwhelming, from what I've seen.  They're now forcing you to use their proprietary camera, no more option for GoPro or other camera mount.  It's a shame for the consumer, but of course it makes sense for DJI from a business standpoint....

Exactly my thoughts, although I wonder if it will be possible to hijack their lightbridge connections, as it was with the Vision+'s FPV. For now, the best option seems to be, to buy a P2v2 (with the upgraded motors and props), and to stick a small compact on it, like the rx-100, Ricoh GR, or if you're brave, the NX-500.

I agree.  I just got a NEX-5, with mounting it on a P2 in mind. It's such a handy little camera though, I don't think I have the heart to endanger it... haha

Ricoh GR would be ideal in my mind... shame they're discontinued and still relatively expensive.

15

General / Re: Camera station questions

« on: April 29, 2015, 03:33:06 PM »

Kind of asked an answered really.  3 camera stations = 3 cameras... and you're wondering why it's not as good as 55 cameras.   

If it's a fisheye lens why are you shooting 20 images per station? Full frame fisheye will get you everything with 5 shots (4 @ 90°, tilted -15° and 1 shot pointing straight up) You'll get a hole around your tripod that will have to be filled with adjacent cameras

The camera positions of all of the cameras are calculated as a single point, and since they are being calculated from a wide range of angles, the calculation of the camera position tends to optimise more accurately than individual cameras, this in turn help to optimise distortion parameters (not much benefit if you're using calibrated values) and in my limited experience so far can produce cleaner point clouds.  If you have a low resolution camera you can also use a longer lens and multiple images to increase the effective resolution.

Gotcha. I figured that 3 stations was the equivalent to "3 cameras", just wanted confirmation.  As to why I was shooting 20 per station - because this is the first time I'd ever tried it, and clearly didn't know better. Now I do. Thanks!

I'm using calibrated lenses for all my handheld work, and I was hoping that the camera station method would work better for doing interiors, but I don't think it will.