Inspire v Phantom for mapping

IrishSights · Oct 16, 2016

Good discussion but drifting a bit off topic

PFAW Holder
BNUC-S Qualified

bluelight.support · Oct 16, 2016

oops sorry

woodc · Oct 17, 2016

After re-reading it seems I am on the wrong wavelength <lol> It seems you gents are mapping smaller areas with a much greater accuracy requirement compared to my mapping of larger pieces of land where the overall accuracy is not as important. Sorry about that. Here is an example of a recent job done with a P4:

Farm:

http://drdp.ly/pl575B

Adjacent Plant:

http://drdp.ly/jtpvnt

This is over 4000 pictures and we were able to hit well below our goal of 1.5 in/px (yes...inches not centimeters ;-)

I1 images at 16MP with either the 15mm, 12mm or even 45mm certainly result in much better resolution however the time trade-off was not worth it for this scenario. We simply fly lower with the P4 to help bridge the difference between the 12MP and 16MP/better glass.

bluelight.support · Oct 17, 2016

woodc said:
Here is an example of a recent job done with a P4:

Excellent quality for 4000 images, how long did that take for processing (online I assume)?

What settings did you use on the camera to achieve that.

I assume this was multi battery - how long did it take?

Peter Syson · Nov 1, 2016

Good morning or whatever!
Use I1 version 1, capture with Maps Made Easy because any change in battery is auto fly home and returns to where it left off.
Then using pix4 for processing.
Having real issues adding GCPs due to differing geo systems.
Pix 4 auto recognise WGS 84 but GCP and output requirement is GDA94. Pix4 places photos in right location but fails in step 1 due to different geo referencing!
This happens on some jobs just not all!

khex · Nov 30, 2016

The reason that i decided to move up to an Inspire was due to wind, and also more lens options for detail inspection work. However, for most standard topographic surveys that we do the Phantom does a fine job. We also fly consumer grade cameras from our manned aircraft and get a gsd of 4 to 6 cm. Both the Phantom and Inspire produce better results but for large # of acres the airplane is hard to beat.

We are happy to assist other folks in the business. We operate in North Dakota and it is cold and windy this time of year so we are slow. We use Pix4d and Context Capture. We specialize in building 3d models for industrial oil and gas well sites. We would be happy to process images and surveys for others that do not want to purchase the software. Also, our camera pods from airplane can be mounted to most cessna 172s and could be used by others in the business take on larger jobs.

Here is a link to an oil and gas well site we constructed using a Phantom 4: acute3d

Frogsby90 · Dec 8, 2016

bluelight.support said:
I would say they are vital. Unless you are able to produce rtk data and process that straight into your data.

My workflow is normally

1 take geo located images via inspire 1 pro
2 readjust the - sea level to + sea level in exif data
3 take into Photoscan Pro
4 align images
5 add gps control points
6 build point cloud
7 build dense cloud
8 build mesh

obvisouly tweaking the options to your fav. settings.

In the meantime, I would go round the site using common sense to take reference ground control points, using fixed furniture and features. Using something like the Geo 6000 with CM accuracy and Terracync and external antenna at 2m, locate your point - add feature, collect data for a good minute or so per point to get a good 60-100 data points (remember the 600 is 1hz) - I also take an image of the point as well which is geo referenced. Its important to note i am not using a realtime RTK data feed here, just the kit which can use rtk real time. In normal mode, this will get anything from 20-60cm accuracy.

I then get the data back to the office, and post process it with Rinex data for the time period and Pathfinder office to create my CSV import file. This will then give accuracy of normally 1-3cm. It is this data I then use in processing.

I cannot see how you can advise accurate analysis for anything geospatial without this process.

I went for post processing as it saved me the £2k per year for data feed but if you don't have financial restraints and good mobile service, then you can get 1-3cm accuracy in the field using realtime.

Hope that helps!

Wow in the US especially Texas where we operate the RTK signal is free to use I've forgotten how much longer it took to do in school with older GPS technology. Definitely have gotten spoiled to just plug in 1-2cm accurate points right after collection into pix4d. We also have surveyors that are partnered with us in Louisiana that operate RTK signals so we are just lucky to be able to use those I guess. I would imagine in the near future as measurements and data need increase there will be in increase in government funded RTK servers for civilian use.