Lee D, post: 391190, member: 7971 wrote: I've seen one or two other posts on here about drones with RTK onboard but I haven't researched them. The GNSS receiver on the UX5-HP is totally passive; it's not used for navigation and is not connected to the autopilot, which has its own meter level GPS. It collects static data at 20Hz so that you can post process your flight lines, and receives event markers whenever the camera is triggered. I would say, based on my relatively limited knowledge and experience, that it reduces the need for ground control because the camera positions are pretty accurate after the flight has been processed. I've done some limited testing - limited because anything involving UAS data processing is time consuming - and the positions obtained without using GCP are surprisingly accurate. But you still need at least a few GCPs to tie you in to accurate coordinates and to ground truth the data.
The added bonus of having the onboard GNSS is that after you process the trajectory you can look at a 3D view and get a very good visualization of the flight path. This comes in handy, especially when, like me, you're trying to learn all that you can about how the aircraft behaves.
I went through the sales pitch, there were drones with and without RTK, both had GPS but the one without RTK the GPS just for navigation. The cost difference was YHUGE, and I couldn't get a good answer why I would want RTK on the drone, would it eliminate ground control? would it way better answer?
I believe it would depend on the price difference. Having RTK should reduce the processing time and the amount of ground control. Is it worth the extra cost? That is an analysis that would depend on several variables like how much it will be used, field cost versus office costs, etc, overall purchase costs, etc.
Good name for a Survey Business:
Right; [USER=3]@Kent McMillan[/USER] ?
I mean; it's got a name in it, right?:smarty:
John Hamilton, post: 391321, member: 640 wrote: I currently have a share in a flying club, 29 members, 3 planes. Sounds like a lot of members for a few planes, but in reality about half or less fly regularly. We have very reasonable rates, much cheaper than renting from a third party like a flying school. Also cheaper than owning a plane under almost any circumstance. the only benefit to owning a plane myself would be that it would always be available on demand. But, having three planes in the club means at least one is almost always available. We have a Skylane (C182), a Cardinal (C177), and a Tiger (Grumman), I only fly the cessnas typically.
C182 is about as good as it gets.
John Hamilton, post: 391340, member: 640 wrote: I believe it would depend on the price difference. Having RTK should reduce the processing time and the amount of ground control. Is it worth the extra cost? That is an analysis that would depend on several variables like how much it will be used, field cost versus office costs, etc, overall purchase costs, etc.
I agree, I just can't see how a drone taking photos with or without RTK can figure out where the ground is without ground control. The RTK version was double, so it needed to have a big advantage, maybe the processing was improved. That was some time ago, things may have changed in the last couple of years.
I got my certificate in a Cherokee 140 at the Playboy Club airport in Lake Geneva back when your certificate number was the same as your SS number. Oh the stories I could tell about icing, bird strikes, and deteriorating VFR conditions. A club that I once belonged to had a Tiger that we used to fly around the Puget Sound area with the canopy open. Those were the days:blush:
MightyMoe, post: 391355, member: 700 wrote: I agree, I just can't see how a drone taking photos with or without RTK can figure out where the ground is without ground control. The RTK version was double, so it needed to have a big advantage, maybe the processing was improved. That was some time ago, things may have changed in the last couple of years.
I would think that having RTK (and ideally some type of IMU) on the drone would mean that the imagery is *ALMOST* correctly rectified right out of the box, which should cut down a lot on the processing time and on the amount of GC needed. If anyone has seen processing of images, it takes a long time for pixel matching, etc just to get to where it knows how it all fits together. But I would still want a fair amount of ground control at this point to tighten it up and give some confidence in the results. But, I think just having static GPS (or GNSS) on board would be just as good as having RTK. By not having RTK you are eliminating some weight. The other advantage of having GPS and IMU on board is to reduce the amount of sidelap required, which is quite high without it (60-80%).
When airborne GPS first came out, it reduced the amount of ground control needed greatly, and it also made the geometry (layout) of GC less critical. Now, it usually has IMU with it, and then helps even more.
I was talking to a Trimble rep at their booth last year in Reno at a drone conference. I asked if his fixed wing had survey grade GPS on board, his answer was no, you just need to set ground control (??). However, I see a definite benefit to having it on board, but not necessarily RTK. Hard to understand why Trimble would NOT put GPS on their drone.
LiDAR on a drone (or a plane) MUST have GPS and an IMU in order to be georeferenced. Being that it flies a lot lower than LiDAR on a manned aircraft, the IMU can be of lesser quality (and hence a lot cheaper).
Does anyone know the cost of the Applanix APX-15 UAV?
http://www.applanix.com/products/dms-uavs.htm
John Hamilton, post: 391367, member: 640 wrote: I was talking to a Trimble rep at their booth last year in Reno at a drone conference. I asked if his fixed wing had survey grade GPS on board, his answer was no, you just need to set ground control (??). However, I see a definite benefit to having it on board, but not necessarily RTK. Hard to understand why Trimble would NOT put GPS on their drone.
Trimble got into the UAS business when they acquired Gatewing several years ago; the product at that time was the Gatewing 100, which was replaced by the UX5. The UX5-HP was not released until early this year, around February, or at least that's when they started shipping them in the US. The survey grade GNSS is one of several enhancements offered on the HP version.
In about 1880 one set of my great-grandparents moved from Ohio to a spot about 50 miles from my current residence. Nice farm of about 240 acres with a school house already setting on one corner of it. Today it is partly occupied by an airport that serves a small town and surrounding communities. Tomorrow there is a scheduled "fly-in" for small plane enthusiasts. A big part of the overall party is free plane rides as long as the pilots are willing to do so. I intend to be there tomorrow with my nine year-old granddaughter. It will be her first flight ever. It will be my first chance to view the former family farm from the air. Hoping it works out well.
My mother's first cousin owned that farm up until his death about 10 years ago so it was in the family for roughly 125 years. This cousin became a pilot during WWII and was still flying up until a short time prior to his death. I'm positive he was the primary reason for the airport being developed as it was. He could walk out his front door about 200 feet to the hangar to fire up his plane.
We don't fly a UAV, but do have three Cessna aircraft and an Aero Commander in the aircraft fleet, two Microsoft Vexcel mapping cameras and an Optech airborne LiDAR system, all equipped with high end GNSS/IMU units (more expensive than any UAV I have seen alone). None of this is flown with RTK, but instead all post processed. I see zero advantage to having RTK on board except you could navigate tighter lines. We still have some ground control (albeit way less than pre GNSS/IMU onboard), there is almost always some shifts of the flight lines to the ground control. At speeds and altitudes we are flying manned aircraft anyway, a small timing error results in large shifts on the ground. We read all the advertising propaganda too and just do NOT see the accuracies that would say you can go sans some ground control. Sure you can if you just want a point cloud or pixels in relative agreement and don't care if it quite matches the ground, maybe tasks like flying disaster sites, etc., where rapid response to get a good enough idea is OK.
SHG
Shelby H. Griggs PLS, post: 391381, member: 335 wrote: We don't fly a UAV, but do have three Cessna aircraft and an Aero Commander in the aircraft fleet, two Microsoft Vexcel mapping cameras and an Optech airborne LiDAR system, all equipped with high end GNSS/IMU units (more expensive than any UAV I have seen alone). None of this is flown with RTK, but instead all post processed. I see zero advantage to having RTK on board except you could navigate tighter lines. We still have some ground control (albeit way less than pre GNSS/IMU onboard), there is almost always some shifts of the flight lines to the ground control. At speeds and altitudes we are flying manned aircraft anyway, a small timing error results in large shifts on the ground. We read all the advertising propaganda too and just do NOT see the accuracies that would say you can go sans some ground control. Sure you can if you just want a point cloud or pixels in relative agreement and don't care if it quite matches the ground, maybe tasks like flying disaster sites, etc., where rapid response to get a good enough idea is OK.
SHG
Thanks, that's what I thought, and I assume LIDAR is different than regular photos, which is what I was looking at
My understanding is most fixed wing UAV's use RTK to assist in tighter flight lines and landing. It also aids in taking the photos at a precise point as they in a parabolic vertical curve. Where the planes propeller shuts down and take the photo at the bottom ( or the top) of the parabolic curve. I may be wrong, this is what I was told by an Ebee pilot. Copter UAV's often don't use RTK, but again those that use RTK use it to aid in tighter take offs, flight lines and landing. Ground control is essential for vertical accuracy, especially where terrain has a lot of relief.
RADAR, post: 391345, member: 413 wrote: Good name for a Survey Business:
I mean; it's got a name in it, right?
And suggests a large intake of recreational drugs so that potential clients are on notice.
A question for the pilots concerning the airport I mentioned above. The runway has a 17 on the north end and a 35 on the south end but it appears to run straight north and south and aligns nicely with the section lines. Educate me.
Holy Cow, post: 391419, member: 50 wrote: A question for the pilots concerning the airport I mentioned above. The runway has a 17 on the north end and a 35 on the south end but it appears to run straight north and south and aligns nicely with the section lines. Educate me.
Runways are numbered to the nearest 10å¡ magnetic, not true
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Holy Cow, post: 391419, member: 50 wrote: A question for the pilots concerning the airport I mentioned above. The runway has a 17 on the north end and a 35 on the south end but it appears to run straight north and south and aligns nicely with the section lines. Educate me.
Here it is 16-34.
Line up on the runway, set your directional gyro to the runway heading, then pour the coals to it.
Stood in line for two hours but it was worth it.
John Hamilton, post: 391442, member: 640 wrote: Runways are numbered to the nearest 10å¡ magnetic, not true
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There are exceptions though. LAX (Los Angeles International), for example, has four parallel runways. To avoid confusion, they're numbered 06/24 L and R, and 07/25 L and R.
rfc, post: 391554, member: 8882 wrote: There are exceptions though. LAX (Los Angeles International), for example, has four parallel runways. To avoid confusion, they're numbered 06/24 L and R, and 07/25 L and R.
You can only have three parallels with the same number-L R and C. So a few places they offset them by 10å¡, I think Denver and dfw do that as well. Pittsburgh has 28L/10R, 28C/10C, and 28R/10L
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This is a pretty good article I was readning this morning.
The Evolution of LiDAR Field Operations and Preferred Methods
http://www.lidarmag.com/PDF/LIDARMagazine_Wrenn-EvolutionOfLIDAR_Vol6No6.pdf
