Messages

1

General / Re: DEM From Mesh or Dense Cloud

« on: August 19, 2016, 12:56:26 PM »

Hi Stihl,

Oh that is a great option .. to model vertical surfaces (acquired from ground) in a fast "height field" mode 

I thought somehow that the red plane of the box defines or refers to the coordinate system .. so should be ll to the xy plane of used coordinate system .

Thanks for the enlightenment  !

bw,m

2

General / Re: DEM From Mesh or Dense Cloud

« on: August 10, 2016, 05:26:51 PM »

Hi Stihl,

Thanks for fast respond!

going to Tools in the menubar and selecting "Reset Region".

Oh, as easy as that ! Great to know.

quote author=stihl link=topic=5357.msg27889#msg27889 date=1470827086]
However, if the bolts that are attached to the wall are too thick, the underside of the attachment wouldn't get meshed as this is out of view for Photoscan when the wall is looked at from directly above.
Then you should choose an arbitrary mesh to generate meshed data for occluded areas  when viewed from above. This will generate a more complete model.
[/quote]

Here are the prints screens of the "bolts construction" on the vertical wall; DPC / mesh model: https://www.dropbox.com/sh/8q2ttgzthwv5on2/AAAClPgqXPPba2unuYldXKS5a?dl=0

Since the photos were taken from a bit lower point, I actually have many points on "bolts construction" downside. But sure, they are not meshed correctly using "Height Field" and yes the option "Arbitrary" takes ages (I stoped the process).

Thus, my question is, if it would work (the meshing), if I rotate the bounding box, so that the red plane is ll with my semi-vertical wall and then chose "height field"?

Thx!

Rainy & cold greets,
Maja

3

General / Re: DEM From Mesh or Dense Cloud

« on: August 10, 2016, 01:43:48 PM »

Dear All,

Stihl, thanks for nice and clear explanation!

Two questions refering to Stihl's text:

This is when Photoscan produces a TIN from only one viewing angle, the one that's perpendicular to the red square from the bounding box. If you have your point cloud geo-referenced you can always reset the bounding box accordingly (it will automatically rotate  the bounding box so that the the red square is facing the earth) when it's not already set up right.

1. How can I "reset the bounding box" so the red plane coresponds to my georeferenced dataset (this is to XY plane)?
2. In case of semi vertical wall that has many objects "hanging out" (reinforced wall with many bolts), would I get a better model (so that bolt constructions would be really model as a square attached to the wall), if I rotate the red plane of bounding box into e.g. XZ/YZ plane and using "heightField Mesh"?

Thanks for the answer in advance!

lg, Maja

4

General / Re: Alignment Experiments

« on: May 27, 2015, 07:14:15 PM »

Thank you for sharing your work .. clear and concise !
lgm

5

General / The accuracy of inner and outer camera orientation parameters

« on: February 04, 2015, 05:52:37 PM »

Dear Photoscan-ers,

We did a fensy model out of UAV imagery (3 cm GSD -> 3 GB orthophoto  ). Thanks Agisoft!
However, one thing we miss ..

Our customer would like to know what is the accuracy of inner and outer camera orientation parameters (or intrinsic and extrinsic orientation parameters).
I exported cameras in PS xml format (thanks James for describtion of the file format http://www.agisoft.com/forum/index.php?topic=2570.0]), then camera exterior parameters in BINGO format .. but no accuracy info here 

How/where can I finde those in Photoscan?

Thanks for the answer in advance!

bw, Maja

6

General / Re: The size of coded markers for UAV acquisition

« on: September 01, 2014, 05:09:39 PM »

Thanks Jeff to share your experiences! Do you maybe have an enample of you "x" target at hand?

I see bigban. Jp, I was thinking about min no. pixels/targed needed to identify target, which is the same as your min angular width. Experiment would for sure be the best way to find it, if only we have time for it

Maybe PhotoScan will implement new targets for aerial surveys and algorithm for their recognition inbetween ?!

lgm

7

General / Re: The size of coded markers for UAV acquisition

« on: August 30, 2014, 03:12:39 PM »

Dear Alexey and bigben,

Thank you for your answers.

Alexey, when do you expect that the automatic target recognition for aerial survey will be ready? Is the curent algorithem for coded marker recognition based on a simple image matching (correlating a photo & the theoretical bit-image) and thus looking for the highest correlation coefficient? Or in other words, is there any documantation how this algorithm works?

Bigben, by saying

Then use this angle to calculate the required width of the marker when photographed from your flight altitude.

you suggest that the PS coded marker size (defined by experimentaly calculated angle) simply increases linearly with the flying altitude? Thus, I could just make the experiment on ground at e.g. 10 or 20 m, having different size targets and then expand the best recognisable target for the planed flying height?

Thanks again!

bw, Maja

8

General / The size of coded markers for UAV acquisition

« on: August 26, 2014, 07:50:44 PM »

Dear all,

We are planing an UAV acquisition at a height approx. 75 m & the GSD = 2 cm. The question is, how big should be the coded marker (printable from PhotoScan) to be automatically recognised and coordinates precisely computed?

It is stated in the Tutorial (Intermediate level):Coded Targets & Scale Bars in Agisoft PhotoScan Pro 1.0.0 that the "central black circle-point on the taken photo is not greater than 30 pix." What would be the minimum requirement (the min no.pixels that the target is recognised)?

There was a discussion in 2012 (Automatic GCP identification), when a right/better marker was searched for .. to be used for mid&far range photogrammetry. Any solutions, we could use now?

Many thanks for any info & advice.

bw, Maja

___________________________________
Maja Bitenc, MSc
University Assistant

Graz University of Technology
Institute of Applied Geosciences
Rechbauerstrasse 12, 8010 Graz, AUSTRIA
Email: bitenc@tugraz.at
Web: www.egam.tugraz.at