Messages

1

General / Re: Reducing file size of Orthomosaics

« on: April 11, 2017, 05:05:59 PM »

Same advice: ECW is perfectly suited to reducing thez size of orthophotos files. A compression to 10% barely doesn't affect image quality. And reading these ECW files (using plugins) is very fast

2

General / Re: Fly Through

« on: February 10, 2017, 01:24:27 AM »

Try Quick terrain Modeler

3

General / Cost of airborne LiDAR ?

« on: February 09, 2017, 09:09:38 PM »

I'm currently writing a report to justify the use of photogrammetry vs Lidar survey. I can't find a reference of how much an airborne LiDAR system to be installed in a dedicated aircraft costs:

- Lidar + recording system, software etc.
- combined RGB camera
- inertial station
- dGPS

Quite surprisingly, I can't find this info on Internet, on providers websites, etc. Only cost / Ha are available, not the cost of the equipment
I have in mind, based on a market analysis done a few years ago, that the entry ticket was about 1 million US$
I guess the prices are quite lower now.
Does anybody have a recent estimate (including reference, if possible).
(I'm not talking about low-precision system to be installed on UAV, but on high performance systems).
Thanks for your help.

4

General / Re: Historical Aerial georectification and mosaic optmial workflow assistance

« on: January 06, 2016, 01:49:21 PM »

I confirm what Photogrammetrix is explaining: Photoscan is not suited to your goals.

I would rather use a georeferenced reference canevas, such as a sattelite image and individually warp each historical photo to match some common reference points found in the satellite image (cross roads, buildings, etc.) using a non parametrical transform.
The "georeferencing" module of ArcGIS 10 is very efficient for this. When all photos are corrected, you can merge them in a single mosaic. To achieve this, I'm using  Avenza's Geographic Imager in Photoshop, but there are plenty other solutions.
Good luck

5

General / Re: 2D Line Drawing from Photoscan Model

« on: December 18, 2015, 04:14:57 PM »

AutoCAD 2015 and 2016 can handle very large point clouds. Clouds must be preprocessed in Recap to generate a proprietary format (.RCP or .RCS) but then it's very fast

6

General / Re: 2D Line Drawing from Photoscan Model

« on: November 22, 2015, 12:22:30 PM »

In Autocad 2016 (and 2015 I guess) you can import very large point clouds (prepared with Autodesk's Recap application) and directly draw on it. There are plenty of efficient tools to make slices in the point cloud, to automatically recognise planes and edges, etc.

7

General / Re: mapping pine plantation problems

« on: November 22, 2015, 12:18:13 PM »

Fly higher and/or use a longer focal length. Both will reduce radial parallaxes

8

General / Re: omega phi kappa import

« on: November 20, 2015, 09:18:52 PM »

even if you can import attitude data, Photoscan won't use them. I also find this limitating, but that's a fact

9

General / Re: Point clouds in Autocad 2016

« on: November 06, 2015, 06:19:51 PM »

What is the difference between .RCS and .RCP files ? If I don't use the possibility of using structurated planes, I don't see any difference, and generating .RCP seems faster. Could somebody please confirm ?

10

General / Re: Point clouds in Autocad 2016

« on: November 05, 2015, 06:25:38 PM »

same results, using a .LAS file generated by Photoscan.
I tried several options regarding cloud decimation, but no significant improvement: Recap recognises some planes, but some are correctly located, other are slightly mis aligned and many are completely wrong.
A pity we cannot select manually the planes we want to use as reference (selecting 3 coplanar points, for instance).
In its current form, working with "photogrametric" clouds (i.e. without known scan stations), the recognition of structure in the cloud is nearly useless.

Is there another solution to generate good reference planes ?
Placing a few UCS is not efficient because I can't snap the UCS axis on the cloud.
Is there a solution to generate a volume precisely matching a part of a cloud (e.g. a wall) and use it as a reference to define a new UCS.
As you can see, I'm a pure newbie in Acad, but I thing this software has great potential
 

11

General / Re: undetected coded markers

« on: November 04, 2015, 11:07:12 PM »

Try maybe to change the settings of the camera to get a larger depth of field, i.e. having all objects sharp (both objects located far from the camera and those located closer).
You get this by using a smaller aperture. This corresponds to highet f-number , such as f 8, f 11, etc.
Of course you have to compensate this by a smaller shutter speed and this strongly suggests using a tripod.
Don't use too high f-number however, becaus ethere is a risk to get diffraction artefacts such as colour fringes.
From my experience, f 11 is a good compromise but it depends on the type of camera you have. Depth of field depends also on the size of the sensor. It is longer on a full-frame sensor camera than on APS-C for instance, hense more risk to get parts of the image blurred.

12

General / Re: Point clouds in Autocad 2016

« on: November 04, 2015, 11:58:47 AM »

I will also continue testing on my side and keep you informed.

First test with another project of a single facade using Dieter's workflow. The main plane is perfectly detected, but secondary planes (such as doors, etc). are missing. I can live with that however.
I wil do more tests on complete buildings (4 walls, roof, etc.)

13

General / Re: Point clouds in Autocad 2016

« on: November 03, 2015, 07:41:24 PM »

Thanks a lot for your help, Dieter

At least this confirms there is nothing wrong on my side.
Any idea about how to reduce the noise in my model ?
I'm using Meshlab and Cloudcompare. Both seem to have some cleaning tools, but I cant find the most appropriate one

14

General / Re: looking for help. Why it is always failed to output right DEM

« on: November 03, 2015, 09:27:10 AM »

Which version of Photoscan are you using ?
Do you have GPS positions for your photos ?
Do you use some ground control points ?

15

General / Re: Point clouds in Autocad 2016

« on: November 03, 2015, 12:58:06 AM »

Hello Dieter

Following your indications, I was able to get some planes in the .RCS file, but these planes are placed incorectly (see attachment)

Thanks for the proposal to test my file.
The .LAS is quite large. Please send me an email adress and I will send you the file via WeTransfer
My adress is xxxxx