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Messages - stihl

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391
General / Re: Is it possible to measure window openings with Ps?
« on: June 26, 2014, 05:02:48 PM »
*snip*

I hope that helps.

Keep me informed about your progress ;-)

Cheers
SAV




Hi SAV,

Interesting and informative post surely. Though I do feel I must add something regarding your attached image. We've surveyed a building facade for water damage before and the illustration that you're showing will not produce the overlap you're searching for. The center of the facade will be generated just fine, but as you're only flying one line near the edges you'll end up with a lot of missing geometry at the sides.
Therefore in my experience with this I suggest that if anyone were to do this, make sure to do pay extra attention to the edges of the facade as you can't generate geometry of something if you've only observed it from one angle.

As for the rest, good post.

392
General / Re: Problem with Dense Cloud Classification
« on: June 26, 2014, 10:47:08 AM »
Hi Mohabon,

I've been playing around with this tool as well. From I know the angle isn't that important in your particular case. If I were you I'd try different values for the cell size and height. It takes some times to get a feel what they all do. For me it's usually a hit or miss, but 'fine tuning' it helps.

As for resetting your ground points before trying new parameters; select ?ll the points with a selection tool (I usually use the circle tool) and go to Tools > Dense cloud > Assign class > to 'Created (never classified)' .. this resets the filter and allows you to try new parameters.

393
General / Re: Single camera scanning thread?
« on: April 15, 2014, 04:17:24 PM »
Again, in this forum are a LOT of user, even more are not registered.. from my view here are active approx 25+- users !!!! So how they "reward" work of us ? they write at least THANX ? no :-(

*snip*
And what do you think you will gain from having everything secretive? A more lucrative paycheck?

Do you honestly think that the 25 people that were viewing this thread had anything constructive to add? Because I think if they did, they would've shared what they know. Instead there are at least 25 people who learned something from this thead. And since when is sharing information a negative thing? Your post baffles me.

394
General / Re: Best settings to remove this type of artifaction
« on: April 14, 2014, 12:49:22 PM »
I'm curious to your workflow as you first align the photos, then optimize (without GCP?) then you build a dense cloud and then you build a mesh from the sparse cloud and not the dense cloud... doesn't make much sense to me. Ontop of that you then delete your previous work by then adding GCP's and optimizing it again.

I've had artifacts issues in True ortho's as well. My conclusion is that it comes down to not enough overlap or blurry photos so it can't find the proper textures to match points on in the alignment process.

What I recommend is following this exact workflow:

Align Photos
- Accuracy: High
- Pair preselection: Ground control
- Point Limit: 500000 (500k!)
- Constrain Features by mask: No

-Add all GCP's

-Uncheck all camera positions and just leave GCP active

Optimise Alignment
-Left at default

Build Dense Cloud
- Quality:  High (Ultrahigh if your computer can handle it)
- Depth Filtering: mild
- Reuse depth maps: No

Build Mesh
- Surface Type: Height Field
- Source Data: Dense cloud
- Interpolation: Enabled(default)
- Face Count High

In my experience, having a large sparse cloud with as many points as possible and then creating an Ultra mild dense cloud from that yields the best results.

After viewing your attachment, my conclusion is that the bottom half picture isn't a True Orthophoto at all as you can see the sides of the buildings. That also explains why you're not seeing as many artifacts (or none at all) it's because PhotoScan simply cuts out the best looking photo for that area, but it's not from a nadir viewpoint. The upper half is a True Orthphoto, just with artifacts due to a not enough dense pointcloud.
Though I could be wrong of course. Perhaps someone from PhotoScan can give feedback on this.


395
General / Re: Big Holes after align pictures
« on: April 13, 2014, 07:31:16 PM »
In my experience, Photoscan doens't leave any holes if you enable interpolation for your mesh generation from the dense cloud. Even though the dense cloud shows holes, if the mesh is interpolated it fills those areas up with pieces from the original imported photo's.

396
General / Re: Big Holes after align pictures
« on: April 12, 2014, 08:10:45 PM »
Can you tell me the effective overlap in the photos by right clicking on the chunk in the workspace tab and clicking on 'show info'.

Do the holes get filled up if you enable interpolation for your mesh?

397
General / Re: Big Holes after align pictures
« on: April 12, 2014, 07:50:07 PM »
What parameters did you use for alignment? Like quality and matched points limit.

398
General / -
« on: April 11, 2014, 04:53:07 PM »
-

399
General / Re: Exporting orthophotos in Pseudo Mercator?!
« on: April 11, 2014, 01:14:29 PM »
thank you for your tip. I'm trying the demo version and as it appears, the software is really an 'all-around' tool.
Since I found out about GM, I never once looked back to QGIS or even ArcGIS.

400
General / Re: Exporting orthophotos in Pseudo Mercator?!
« on: April 10, 2014, 11:00:38 PM »
Hi Patribu,

If it's large Orthorectified aerial photo's you're talking about I can strongly suggest the software Global Mapper. In my personal experience it is th? best GIS out there to rendering large files. In size or resolution. Ontop of that it can basically import and export anything. I'd take a look at their trial to see if it will load your image faster than Q-GIS. My bet, it definitely will.
From there on you're free to transform whatever you wish.

401
General / Re: Build mesh
« on: March 28, 2014, 04:37:38 PM »
PM sent.

402
General / Re: Build mesh
« on: March 28, 2014, 03:55:33 PM »
Hello anabento,

Your project sounds similar to what I do. (I'm on the latest Photoscan build) After I've generated a mesh from the dense cloud I export the model to an ARC ASCII grid format and then import it on another software package called GlobalMapper. Superb program, imports/exports any file and it's really fast. It's an extensive GIS program that can do all sorts of calculations, more specific things than what you can do with Photoscan. Of course the great software of Photoscan is needed to get a model in the first place.

As for the holes in the model, try building the mesh with interpolation enabled. Else you can interpolate the holes in GlobalMapper as well.

Is your photograph overlap at least 60%?

403
General / Re: GCP error low - high errors on DEM
« on: March 19, 2014, 12:30:44 AM »
Hello Alexey,

It has been brought to my attention that the lens that I used is most likely the culprit of the deformation, thanks to the lens image stabilization that was turned ON.

In the end, GIS works by "Garbage In, Garbage Out". I suspect new photographs will have to be taken.

404
General / Re: Importing georeferenced .obj model to Meshlab
« on: March 17, 2014, 10:22:48 PM »
Yep he looks dead, nice model!

Could you tell me what's keeping you from using local coordinates, as this model appears to be quite small so I personally see little use for a coordinate system.

405
General / Re: GCP error low - high errors on DEM
« on: March 17, 2014, 08:02:52 PM »
I've checked the GCP heights on the DEM that I made. Even though I told Photoscan that the marker accuracy is 0 the height at those exact GCP locations is way off.
Photoscan was talking about an error of 3.6 centimeter however the GCP's that should match 1:1 in height do not match at all, and in some cases the error is up to 40cm!

How is this explained? Photoscan says the error is low, I've told it that the marker accuracy is 0 and thus absolute but it doesn't use those absolute heights for DEM creation.

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