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Author Topic: Advice for Workflow on big area in city needed  (Read 4569 times)

Tunkali

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Advice for Workflow on big area in city needed
« on: February 10, 2016, 03:05:38 AM »
Hello everyone,

I got a new project for VR architectural visualisation and I need a 3D representation of a big part of the inner city (19ha, located in germany). Because of the VR experience there is a need of a high resolution. Quality of Google Earth is Minimum (Buildings, not Terrain). The mainfocus on the project is emotion and a consitency. A patchwork of different quality methods would break this.

Important places will be definitly covered with a drone and get a single photogrammetry each of them. The other places should maybe covered also with a drone (on higher altitude) and maybe satellite images. My problem is, that it is very hard to access high res satelliteimages which are usable for Photogrammetry. And it seems to cover the whole region with drones will be very expensive in money, time and datasets. There are a lot of high and complicated buildings and there will also be a ground view from egoperspective. My last project suffered a lot of low quality on walls from buildings because the droneflights covered a lot of roofs in high quality but the facades where underrepresentated.

Does anybody of you have experiences with similar projects? What is your advice? Is there a golden way how drones should fly? Do you know a workflow for working with satellite images?

Thank you very much for every advice you can offer to me :-)



Wishgranter

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Re: Advice for Workflow on big area in city needed
« Reply #1 on: February 10, 2016, 04:17:31 AM »
Hi Tunkali 

Get a airplane and good fast SD card and get plenty of images, best if can do  multiple height levels

If possible send me info on the area so can better say what lens and camera will need to solve it...
  muzeumhb@gmail.com
----------------
www.mhb.sk

Tunkali

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Re: Advice for Workflow on big area in city needed
« Reply #2 on: February 10, 2016, 04:36:25 PM »
Hi Wishgranter,

I think that an airplane will be to expensive and a lot of afford (also for equipment, the right technique for good quality images, etc).

I called the state office for geoinformation, and the they can give me georeferenced laserscandata pointcloud with an resolution of 4pts / meter for 84€ / km². This will be a good quality for mid distant objects. So I could focus on near objects for drone flights maybe. The question is, how can I map texture data on this pointcloud / meshed model. I am afraid that Satellite data resolution is not high enough? Do I need special software or can I achieve this with Photoscan?

Arie

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Re: Advice for Workflow on big area in city needed
« Reply #3 on: February 10, 2016, 06:27:01 PM »
You can use Agisoft to texture laserscan data.

After aligning and referencing the images, just import the referenced mesh of the lidar data and texture it.
Just make sure, that the referencing of the lidar data and the images is accurate (using dgps or total station for GCPs). When the alignment between the datasets is not good enough, there will be some errors in the texture map.

In case the aligment based on reference markers isn't precise enough, you can export a mesh of the dense reconstruction and align it using an ICP approach such as implemented in Cloudcompare.

I do this regularly and it works great.

Tunkali

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Re: Advice for Workflow on big area in city needed
« Reply #4 on: February 11, 2016, 03:32:42 AM »
Thank you! This sounds like a good plan :-)

luffatt

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Re: Advice for Workflow on big area in city needed
« Reply #5 on: March 13, 2016, 09:34:51 AM »
You can use Agisoft to texture laserscan data.

After aligning and referencing the images, just import the referenced mesh of the lidar data and texture it.
Just make sure, that the referencing of the lidar data and the images is accurate (using dgps or total station for GCPs). When the alignment between the datasets is not good enough, there will be some errors in the texture map.

In case the aligment based on reference markers isn't precise enough, you can export a mesh of the dense reconstruction and align it using an ICP approach such as implemented in Cloudcompare.

I do this regularly and it works great.

Hi Arie,
would you share your workflow more in depth ?

Thank you
Luciano

Packy_GIS

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Re: Advice for Workflow on big area in city needed
« Reply #6 on: March 15, 2016, 02:53:41 AM »
If you guys are still looking for an airplane to hire - we have a small airplane equipped with camera + stabilization used for SFAP. Our aircraft is parked in the Czech Republic by the border with Germany (Dresden - Chemnitz level) and we have a photo-licence for flying in Germany.
The price is approx 200€ per hour (flight speed about 80km/h) - from 300m altitude we have 2.5cm/pixel - from 1000m ca 22 cm/pixel.
Packy
Here is an example of our output: http://fzp.maps.arcgis.com/apps/webappviewer/index.html?id=16559e1456044b41a93e369a19e402fd

Arie

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Re: Advice for Workflow on big area in city needed
« Reply #7 on: March 29, 2016, 12:56:39 PM »
Hi Luciano,
sorry for the late reply.

Are you talking about registering a dataset without common GCPs?
Cheers.