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Messages - Santiago

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16
General / Urgent! Aerial Triangulation File, Format inquiry
« on: February 09, 2016, 10:54:10 PM »
Hi,

A client is asking for the aerial triangulation files. I'm trying to figure out which files, of all the files I can export with Agisoft, are the ones he needs and how can I open them and view the AT files. Not sure if this files are the camera positions or the matches (or if some other file), which I can export by going into tools, export, cameras or matches. My client uses ArcMAP to view the files so I would need a format compatible with ArcMAP.

They didn't specify a format.

Thanks for any help and best regards,

Santiago T

17
General / Re: Measurement Accuracy
« on: June 12, 2015, 08:54:00 PM »
Hi ankur6ue,

Have you tried using markers that you know exactly how much they measure. I tried it once for a 3d modellin of a vehicle and the accuracy was very good. You could try measuring a corner of the house, where you would give that corner a starting point of 0, 0, 0 in XYZ or lat, long, alt. Then you could create 3 end points and in markers input the distance between the corner and those 3 end points.  Having done that everything would be scaled based on those know points. You could do this for several parts of the house which you know exactly how much they measure (by using a measuring tape).

I think this should work. Sorry if it isn't clear enough.

Best regards,

Santiago

18
General / Re: Mapping Vegetation and agriculture
« on: January 26, 2015, 07:34:32 PM »
Hi Sultan,

Try creating a final mesh with only the ground points (creating a DTM), be sure to leave only the ground points when selecting them because the automatic tool to do this doesn't work perfectly. After that try exporting the orthophoto again and see if the result seems better. Follow this link to the tutorial on making a DTM with agisoft http://www.agisoft.com/index.php?id=35

Best regards and hope it helps,

Santiago

19
General / Re: Memory consumption for EXPORT TILES
« on: January 05, 2015, 09:42:29 PM »
Hi I'm getting an intant crash when trying to export tiles. I've tried several parameters for the tile and pixel size of the model. I want to try the agisoft viewer. Does anyone else has this issue. The issue just says can't export model and this error doesn't occur when exporting the 3D model.

Best,

Santiago

20
General / Mosaic Resolution, Orthophoto Resolution
« on: October 08, 2014, 05:35:14 PM »
Hi,

I have the following issue with a very huge project I'm working on. I have over 2000 images taken between 250-400 m above terrain in a very variable terrain. The project consists on 86 km from which I made two flight lines. The terrain varies from 2000 m above sea level and goes to nearly 1000 m above sea level, if this matters. The images all have very good overlap and I've been having mainly 2 major issues.

1. I can't manage to align the images correctly although I have the GPS position for everyone of them. I haven't tried chunks because I've never worked with chunks before and I'm afraid the merging will not be as good as if I process everything in a single run, although I may be wrong. If anyone has had good experience with chunks please let me know.

2. I've managed to create 2 separate projects were all the images are aligned. Using this I created 2 mosaics, but the issue I have now is that the mosaic creation is telling me the resolution will be around 50 cm when the resolution should be between 10-15 cm or so.

I've attached an example of the image with the worst resolution during the flight and a zoom in showing the resolution it has. The final resolution should be something similar to this I believe.

If someone knows how I should approach this project please let me know.

Best,

Santiago

21
Hi dyrvar,

I think what you're seeing is the bowl effect. What's the accruracy of the GCP's you're using? This might be the cause of the bowl effect you're experiencing.

Please check this link for a solution. hope it helps.

http://www.agisoft.ru/forum/index.php?topic=600.0

Best,

Santiago

22
General / Re: Wavy trees and errors ob building edges
« on: June 19, 2013, 01:54:23 AM »
Hi Herman,

Thanks for your reply. So you say the building edge issue is because of relief distortion. For what I understand about relief distortion, is that's one kind of geometric distortion that occurs for taller objects that are further away from the center of the picture, but in this case that building is in an image that contains the whole building pretty much in the center of the picture. But if it was certainly caused by relief distortion what can I do to correct this issue, because I would most likely love to present an excellent final result to my clients. I attach the image where the building is contained almost in the middle.

When you say movement between pictures in the vegetation issues. Do you mean like movement of the UAV that causes blurry or tilted pictures or what do you mean exactly?

One thing I forgot to say is that I dind't use any GCP's, I'll use some next time to see if there are any improvements.

I would love to see some good results any of the users of Agisoft have of building edges, just so I know it can actually be achieved without any mosaic editing tools, or if i'm just expecting something not yet possible.

Best regards to all and thanks Herman,

23
General / Wavy trees and errors ob building edges
« on: June 11, 2013, 06:28:49 AM »
Hi everyone,

I was wondering how could one avoid this mistakes on the orthomosaic and is everyone getting this kind of mistakes always, or are you getting true orthomosaics with perfect quality.

What are the causes of this mistakes? Incorrect camera parameters? Poor overlap? Altitude of the flight? Type of lens used?

Thanks for any help and guidance you guys can give me and many others who I'm sure face this same issues.

Best regards,

Santiago


24
General / Re: Synchronizing GPS clock and camera Clock for geotagging
« on: June 04, 2013, 03:30:50 AM »
Thanks guys

You both have been very helpful I'll give it a try and let you know.

Best regards,

Santiago

25
Synchronising GPS and camera clock is quite easy: just take a photograph of the GPS time displayed on a handheld GPS device (including seconds) before and/or after the flight. It does not have to be the same device as the one that's flying with the UAV, because all GPS devices are synchronised via the satellite signal. Just make sure that the GPS already sees satellites and has established its position, otherwise its time may not have been synchronised to the satellites yet. After the flight, look at the photograph showing the GPS time: subtracting the GPS time from the photograph's time stamp (under file... properties... details) will give you the corect offset. Then, you can use this offset to put it into a geotagging software together with all photographs and your GPS track to assign the correct GPS position to each photograph. Alternatively, you can calculate the correct time and assign the correct GPS position manually or using a spreadsheet software like Excel.

P.S.: Be aware that the flight velocity of you UAV will have an influence of position accurracy: camera time stamps do not include fractions of a second, so your synchronisation is only approx. +/- one second. At 20 m/s flight vecocity, of course this results in a position error of +/- 20 m in addition to the GPS error of +/- a few metres. Flying a lawnmower pattern you can hope (bout not be sure) that much of that error will be cancelled out.

Hi Ralph,

Thanks for your reply. I did try using a handheld device to synch the camera to it, but my handheld GPS doesn't display the time or at least I wasn't able to find it, also there's the issue with the camera which doesn't show me more that minutes. It's a sony nex 5 so if anyone knows if the time could be displayed as 12:00:00 that would be great. Thanks anyway Ralph at least I know how it must be done now. Also which geotagging software do you use, right now I'm using geosetter, but with it I have to geotag one image at a time, I would want a software that allows me to do a more efficient geotagging.

Best regards and thank you,

Santiago

26
General / Synchronizing GPS clock and camera Clock for geotagging
« on: May 09, 2013, 01:27:36 AM »
Hi all,

I have the following inquiry. I work with multirotor UAV's for mapping purposes. I have to geotag each photo by using the route I planned so I just plot in the lat and long of the waypoints I planned. I know this final method may result in an error augmentation do to positioning errors the kopter has in the air.

I've seen in some websites that the camera's clock should be synced to the GPS UTM clock. To be sincere I have no idea how to do this, I don't even know how to look at the clock of the MK's GPS. I've looked in many forums, but I haven't found anything useful. Also another problem I see is that the way the time is displayed in the pictures my camera takes (Sony Nex 5 and 5N) has only precision of minutes. For example 12:34, not 12:34:23. Hope someone can help me out by telling me how to synchronize them and use this data to geotag the pictures with more precisi?n, probably using the GPX data from the mikrokopter.

Thanks and best regards,

Santiago

27
The Sony Nex 5, 5N or 7 are all great choices. They are low in size and weight, which can be controlled with an infrared controller by your RC. They also have interchangeable lens which will give you an advantage for what you're looking. Either way you should always take into account the size and weight of the camera and that will depend on which UAV you have. If you have a multirotor they can handle many cameras, but the heavier, the less flight time you'll get.

In my opinion the sony Nex 7 is one of the best cameras out there for low altitude aerial photography, but if you aren't looking for something that good the sony nex 5n will do and it is between 600-700 US$.

Regards,

Santiago

28
General / Re: Transmission line profile mapping
« on: April 01, 2013, 07:44:55 AM »
Thanks guys,

Lui I agree with you, the best option here would be LIDAR, but I have to say what Phisan posted is truly interesting. Although when looking at the accuracy XEOS can achieve even when using ground control points (20 cm vertical and horizontal), can't compare to LIDAR.

I'll look more into SimActive's Correlator 3D, it seems interesting, but I get a feeling it's not design for every UAV with a common camera out there. Unlike Agisoft or Pix4d it does ask for orientation parameteres like angular values, which I can't obtain from my UAV's.

Regards,

Santiago

29
General / Transmission line profile mapping
« on: March 18, 2013, 08:45:09 PM »
HI,

A company asked me to do the following job for them, but I really don't know if it could be possible with photogrammetry. We have a Hexacopter and a Lehmann Lp960 for aerial mapping equipped with a sony nex 5n 16 mp. The job consists in:

Create a profile on some transmission lines (power lines) that extend 150 km. They need to know were the lines are with respect to the terrain (including vegetation so no need to remove it). What I don't know is if the photogrammetry techniques can accurately model this transmission lines. Here's an example of what they need.

http://www.powerlinesystems.com/pti/ptipaper.html

I think that this job could only be done accurately with terrain techniques or LIDAR, or if anyone here has had any experience with a similar job It would be great to know your experience.

Thanks

Regards,

Santiago

30
General / Re: Trees!
« on: March 10, 2013, 12:34:46 AM »
Hi Herman,

Thanks for your reply. I know what I was doing wrong now, I was exporting the .las file in WGS84 and it had to be exported in a projected system (meters not degrees). Still after processing the data I wasn't getting any good results so I tried talking with Martin Isenburg, the creator of lastools. He asked me to send him the file I was creating and afterwards he answered this on a thread. If you guys are interested you can look at it here: https://groups.google.com/forum/?fromgroups=#!topic/lastools/oK81EEr7W3Y

Also it seems global mapper can handle some of that data much better than ArcGIS, I'll give it a shot.

Regards,

Santiago

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