Simple Photgrammetry help

timeforprunejuice · Nov 5, 2018

Hi Folks,

I am a teacher and I want to learn photogrammetry using my solo with a GoPro 4. My first simple questions are:

1) How fast does a solo go by default on a 'Mission'
2) What speed should I use for photogrammetry as a start
3) Default time between photos to start?
4) Photo or video? - I assume photos
5) I have Recap, what gets uploaded in Recap?

Thank you
tfpj

Saijin_Naib · Nov 5, 2018

1) Depends what GCS you use.
2) Depends upon a vast number of factors.
3) Depends upon a vast number of factors, normally you can let the GCS determine this.
4) Depends, though I personally recommend photos.
5) No idea, never heard of it/used it.

Personally:
1) 30mph @ 400ft relative to terrain
2) 30mph @ 400ft relative to terrain
3) 85% overlap determines the resultant photo interval
4) Protune JPEG, everything off/neutral
5) MissionPlanner + Tower, and a number of other programs to process the data

wuwuwu · Nov 6, 2018

timeforprunejuice said:
Hi Folks,

I am a teacher and I want to learn photogrammetry using my solo with a GoPro 4. My first simple questions are:

1) How fast does a solo go by default on a 'Mission'
2) What speed should I use for photogrammetry as a start
3) Default time between photos to start?
4) Photo or video? - I assume photos
5) I have Recap, what gets uploaded in Recap?

Thank you
tfpj

My son is doing pictures (you could extract them from a video but I don’t know about the resolution.)

Speed he controlling manual, but I would recommend as slow as possible (the GoPro is doing 1 pic every 5sec) and you need as much pics as you can get .
Here are some pics from his first model:

wuwuwu · Nov 6, 2018

Saijin_Naib said:
1)
Personally:
1) 30mph @ 400ft relative to terrain
2) 30mph @ 400ft relative to terrain
3) 85% overlap determines the resultant photo interval
4) Protune JPEG, everything off/neutral
5) MissionPlanner + Tower, and a number of other programs to process the data

30mph is already fast..it’s around 15m per second what means on 5s between the pictures you have done already 75 m (sorry guys, I am a metric )

Saijin_Naib · Nov 6, 2018

wuwuwu said:
30mph is already fast..it’s around 15m per second what means on 5s between the pictures you have done already 75 m (sorry guys, I am a metric )

Who said my picture interval was 5s?

With over 3000 acres surveyed, I've vetted my parameters quite well at this point. 30mph is fine if you operate properly. If it works this cleanly on Agricultural Fields, which tend to be more difficult/demanding for photogrammetry due to large areas of nearly homogeneous points, you can expect better performance in areas with more unique/identifiable features, like suburban/urban areas.

View of Mesh:

yarrr · Nov 6, 2018

timeforprunejuice said:
Hi Folks,

I am a teacher and I want to learn photogrammetry using my solo with a GoPro 4. My first simple questions are:

1) How fast does a solo go by default on a 'Mission'
2) What speed should I use for photogrammetry as a start
3) Default time between photos to start?
4) Photo or video? - I assume photos
5) I have Recap, what gets uploaded in Recap?

Thank you
tfpj

1. I think the default is 25mph. In my experience, this is too fast- especially if you're trying to get a point cloud/dem rather than just an ortho.
2. So, I set my mission speed to more like 13mph. (also a metric guy- 6m/s).
3. The GoPro/Solo interface is quite unreliable. Mission Planner/Tower can automatically determine interval and trigger the camera- but it often fails. So typically I set the GoPro at a 2 second interval. 1 second gives more data, and you could fly slightly faster. Basically you want to target a 70% overlap, 70% sidelap- which based on your lens determines your flight height. I typically fly at 60-70m elevation with a 5.4mm lens.
4. Photo- per settings listed by Siajin
5. You need to geotag your images - via Solex, Geosetter, or Mission Planner. (Tip- 'set' the Gopro 'time and date' before each flight. Then the "time offset" in Mission Planner is close to 0, usually -1.82 seconds). Then feed geotagged images into Recap. Note that Recap is not nearly as reliable as many other options. If I were you I'd start with something simple like MapsMadeEasy or DroneDeploy, then move to PhotoScan or Pix4d. I also use Recap (via the rest of the Autodesk AEC suite) but it is pain to get good results.

Good luck.

Saijin_Naib · Nov 6, 2018

yarrr said:
1. I think the default is 25mph. In my experience, this is too fast- especially if you're trying to get a point cloud/dem rather than just an ortho.

I'm happy with my results. Granted, I've not done built-infrastructure survey, so you're likely correct in that lower/slower might be more advantageous, but if you're going for natural environment collection, I think these parameters are appropriate.

yarrr said:
3. The GoPro/Solo interface is quite unreliable. Mission Planner/Tower can automatically determine interval and trigger the camera- but it often fails.

After putting my GoPro on firmware v5 and (over)spending on a UHS-II mSD card, I've found that I am reliably able to nail my photo interval of just about 1.6s, giving me my 85% overlap (+/- a few percent) with my settings. I can't stress how much of a reduction in headaches getting a really quality mSD card has made in my collection. Well worth the spend, IMO.

timeforprunejuice · Nov 6, 2018

Great information guys. I have plans to test the next few weekends ... I have Mission planner and I've ordered an Android tablet for Solex. We have a lot of construction going on at the closed Naval ship yard and I want to photogram(?) their buildings ...

More later ... I plan to start start slow - maybe 1.6fps and 25mph using the GoPro 4 on my Solo.
tfpj

Saijin_Naib · Nov 6, 2018

timeforprunejuice said:
We have a lot of construction going on at the closed Naval ship yard and I want to photogram(?) their buildings ...
More later ... I plan to start start slow - maybe 1.6fps and 25mph using the GoPro 4 on my Solo.
tfpj

I'd take yarrr/wuwuwu's advice more to heart if you're doing built survey, especially if you want to get oblique Imagery for the sides of building/structures. My settings are really tuned/optimized for aerial Nadir survey. You can always combine different projects/collect events together, as well. So do your oblique collection low/slow (below 20mph for sure, especially if you're going to be close to the ground/surface to be imaged), and potentially take another aerial Nadir collect and merge the results, if needed.

timeforprunejuice · Nov 6, 2018

Low and slow ...

I know how to set a point of interest, but would I want to fly the Solo sideways? 90 degrees to actual flight, facing the building? Is that possible?

Saijin_Naib · Nov 6, 2018

timeforprunejuice said:
Low and slow ...
I know how to set a point of interest, but would I want to fly the Solo sideways? 90 degrees to actual flight, facing the building? Is that possible?

Absolutely is possible, especially if you fly slow enough and in calm conditions, as the gimbal will be more than able to compensate for the roll axis, keeping the images nicely level.

timeforprunejuice · Nov 7, 2018

I appreciate the conversation and help.

Thanks ...

Saijin_Naib · Nov 7, 2018

timeforprunejuice said:
I appreciate the conversation and help.
Thanks ...

Will you be making an autonomous flight plan to do this collect? I don't collect manually simply because it is too difficult to ensure consistent flight paths and resultant sidelap/etc.

Mission Planner has some great survey options, and Solex I hear is very competent as well (never used the Missions feature, myself). If you find a legacy version of Pix4D for Android/iPad they had beta Solo support that also works nicely and is very much a push-button solution.

timeforprunejuice · Nov 11, 2018

Hey Folks, I appreciate the support. Even with some gimbal issues - no camera feed - I was able to plot and film a local park under construction using Solex and Mission Planner. I also learned zip line and orbit today. I’ll update all of my firmware tonight and try to get the camera to display remote and do
More experiments tomorrow.
Tfpj

timeforprunejuice · Dec 3, 2018

Hey Folks,

I came pretty close. It seems you should not use wide angle on the gopro as it is fisheye and that causes a failure when uploading files to recap. Once I get this going, I'll make a Youtube video with all of my new found information. I have not had time to refly without using wide angle - hopefully this weekend ...