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Author Topic: Flood Simulation experience?  (Read 2322 times)

GrinGEO

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Flood Simulation experience?
« on: February 01, 2019, 06:26:34 PM »
Dear Agisoft users

Im wondering if someone here has an expertise in flood simulations done with Agisoft Output. I refer to large area fotogrammetric scanning of 1-2 kmĀ² and DEM creation. I have done some experiments in Blender, but the fluid calculation when importing a 3D model from Agisoft (STL format) is so slow that it probably takes 20 days becouse of the high poligon amount.

If someone has any idea how to improve this or using other programs, I would be very happy.

Thanks a lot

Mak11

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Re: Flood Simulation experience?
« Reply #1 on: February 01, 2019, 06:38:26 PM »
You will certainly have more help on this subject by posting this in the relevant forums (https://www.blender.org/community/) as this doesn't have much to do with Metashape IMO. Fluid simulation does take a lot of processing ressourcse (depending on the resolution etc) so there's no easy solution for it.

Cheers

Mak

GrinGEO

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Re: Flood Simulation experience?
« Reply #2 on: February 01, 2019, 06:49:07 PM »
sure, Im already in the Blender Community but I would like to know from Agisoft users if someone here is doing this kind of stuff. Maybe this person tell me to use completely another tool and I could go for it... ;-)

Dave Martin

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Re: Flood Simulation experience?
« Reply #3 on: February 02, 2019, 01:28:42 PM »
GrinGEO,

I don't know how it would inter-work with STL output from PhotoScan/MetaShape, but I do quite a bit of this type of modelling using LAS/LAZ and orthophotos - so it might be worth trying alternative formats if you can (I use GlobalMapper and loading takes sometimes a couple of minutes for a couple of square km and then changing virtual sea-level in synchronised 2D and 3D just takes a second or two every time you click for an incremental rise.

If you're after doing watersheds, then my preferred tool for that is Surfer from Golden Software.

Dave
« Last Edit: February 03, 2019, 01:19:31 PM by Dave Martin »

GrinGEO

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Re: Flood Simulation experience?
« Reply #4 on: February 02, 2019, 03:06:09 PM »
Dear Dave
Thank you very much for your reply. LAZ could be done in Agisoft, but I guess only for the Point Cloud. How do you export Orthofoto & DEM in LAZ so that it can be used?

Can you show up some examples of what you are doing and how you do the simulation? Do you just rise the water level like it would be a plane?
https://www.youtube.com/watch?v=pFe-dMXgorw

Dave Martin

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Re: Flood Simulation experience?
« Reply #5 on: February 02, 2019, 04:53:15 PM »
GrinGEO,

I haven't anything I can share right now, and am not in front of my GIS workstations so can't even screenshot right now, but some quick points:

There's no need for LAZ - LAS will do fine (LAZ is just an *open* compression mechanism for LAS).

I don't use a combined LAS/LAZ and ortho, or indeed a colourised point cloud. The LAS, and ortho if used, are completely separate ingredients.

Depending on the context, I sometimes do water level work with just a coloured elevation scale like in that video you linked to, other times I will overlay an orthophoto on a DSM to show more detailed impact.

In GlobalMapper I just import either (i) LAS DTM or (ii) LAS DSM + ortho. If using ortho, I then overlay the ortho - so long as both are geo-referenced that's all that's needed, and the DSM and ortho can have different sources.

In GlobalMapper I then activate 3D, click on the [enable water level] button and use the [water level up] / [water level down] buttons to adjust the water level; as you click up/down a box on the screen tells you how high the water is at present. I usually use 0.5m increments; you can set the increment and the starting water height.

Regards
Dave

GrinGEO

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Re: Flood Simulation experience?
« Reply #6 on: February 03, 2019, 07:42:48 PM »
Ok Dave.
Thanks this helped a lot...