Canon | UC 900 color | Skyhook - Skyshot Operating Protocol - UCCE Plumas

Skyhook/Skyshot Helikite Standard Operating Protocol
Updated: September 1, 2014
Introduction
A Helikite is an inflatable, tethered hybrid flier that consists of a disk-shaped helium
balloon, a kite, and an aerial photo bracket. The balloon provides buoyance to loft into
the air, the kite provides orientation and stability against the wind, and the bracket allows
you to connect a suitable digital camera for continuous collection of photos.
See http://www.allsopp.co.uk for details, options, and pricing. The unit comes from the
UL and the cost is roughly $1,500 for a basic 1.6 m3 Skyshot that can loft an appropriate
10-15 MP digital camera.
Purpose
This technology enables the user to collect aerial photos in the 0-500’ altitude range. It is
then possible to mosaic the images together using appropriate software, such as Agisoft
Photoscan.
If one desires to “georectify” the mosaic so that it may be used to overlay on other
imagery or data, then it is necessary to lay out and survey ground-based aerial targets.
These can be used in ArcGIS to create match points between data points and targets in
photos. The more targets used and the more distributed throughout the area of interest
the better. Any photo areas outside the region bounded by the targets will not georectify
and will look badly warped.
Ground-Based Aerial Targets
It is recommended to purchase or create aerial targets that you can place on the ground to
establish known points with known geographic coordinates. Thin plywood sheets 2’x2’
square are ideal. They should be painted black with very large white letters on them. The
important thing is to have high contrast with the ground. For shallow underwater
locations, you can take a 5-gallon bucket and place into it cobbles painted with bright
fluorescent colors. These markers won’t be numbered, but you can see them clearly in
aerial photos and they can hold up against low to moderate velocities.
There also exist commercial aerial targets that you can buy at stores that serve surveyors,
such as California Surveying and Drafting in Sacramento, CA.
Buying Helium
1. You need a vendor to get helium. There is a long-term national shortage in
helium, so it can be challenging to get it, so plan ahead.
2. A primary vendor for helium in our region is Airgas, which is located Woodland,
Sacramento, Yuba City, and elsewhere.
3. Check with your institution to see if you have an account and what that number is.
Then call Airgas, give them your account number. Call ahead to make sure they
have it on hand.
4. The first time you go, they will give you a full tank. We usually get one 80 cubic
foot (cf) tank or two 40 cf tanks.
5. If you have one or more empty tanks, then take those and exchange them at the
store for a new one.
Blimp Transport
6. Before leaving campus, be sure that you have all supplies needed by using the
blimp field checklist. Check that you have all items on the list and you are ready
to go.
7. Items loaded in the truck bed are the helium tanks, blimp, car battery, wooden
tiles, and linoleum tiles.
8. First load in the helium tanks and secure them to the truck with the clamp straps.
Use one strap around the bottom of the two tanks to secure them together. Use a
second strap to secure the two tanks to the truck, using the hook on the truck rack
at the truck cab to help hold the strap in place during transport. Use a third strap
to secure the tanks to the truck at the neck of the tank safety caps.
9. Place the 12 volt battery between the wheel well and the inside helium tank,
against the side of the truck bed.
10. Now load the blimp and tarp diagonally across the truck bed. Place the wood tiles
equally across the tarp then spread the linoleum tiles evenly across the tops of the
wood tiles to hold everything in place. The driver should watch for tarp blowing
up from the truck bed – and stop to rearrange the tiles as soon as this occurs.
With all tiles evenly spread, this should not happen, but you should check the
arrangement from time to time.
11. All other equipment goes into the truck cab.
Tile and Blimp set-up
12. Once at the site, set up tiles and GPS their coordinates before doing anything with
the blimp. This is the most time consuming part of the whole effort. The more
tiles you lay out, the more tiles you will get in a photo closer to the ground and
the better the ability to accurately stitch together the photos. Make a crude map of
tile numbers and locations so that you can match up pictures and tiles for analysis.
13. Prepare the helium tank using plumbers tape on the connector and tightening the
pressure regulator onto the helium tank. Open the tank valve and check for leaks.
I found that there was a small leak even with plumbers tape, but not too bad
(could be the individual tank).
14. Attach the clear plastic hose to the helium tank hose barb. When putting away
equipment, be sure this item is on top of the pressure regulator rather than
underneath it, to prevent damage to the hose.
15. Move the tarp and blimp to the top of the truck cab. Determine the blimp’s
direction – the input valve has to be adjacent to the tank so that the plastic hose
remains attached to the blimp during the fill procedure. Be sure the two release
valves on the opposite side of the blimp are closed before starting to fill the blimp.
16. At this point, attach the blimp to the truck with a green clamp strap. Use the
white blimp loop located near the junction of the stays for this attachment. It is
very important that the blimp is attached to you or to a solid object at all times!
17. Now attach the black-taped end of the hose to the blimp, and turn the smallest
knob on the pressure regulator to begin filling. If the helium is noisy at the input
valve, simply open the small knob some more. The large knob can also be
manipulated. I believe it regulates how fast the helium from the tank can flow
through the pressure regulator.
18. It does not take long to fill the blimp, about 5-10 minutes. There is a string that is
attached at the top and bottom of the blimp that assists in navigation. While
filling, position this string so that as the blimp tightens, the string on the fill side is
positioned close to the input valve and the string on the far side is positioned
between the two release valves.
19. Toward the end of the fill, it is possible that the pressure inside the blimp will pop
the plastic hose off of the input valve, so you may want to hold the valve/hose
connection at this point. Note: the whole valve pulled out of the blimp during one
deployment as I was pulling the plastic hose off of the valve. The valve is now
inserted further into its opening and seems to be doing fine. The position of the
valve no longer permits the valve cover to attach to it. This does not seem to be a
problem either in flight or in storage.
20. The amount of helium used to fill the blimp is ~ 900-1000 psi. An entire helium
40 cf tank holds ~1800 psi, so you can get 2 fills per tank.
21. The blimp is full when the strings are tight and the multiple creases at the seam
are smallish. Remember that the goal is not how much helium can we get in the
blimp; all we want is enough loft so that the blimp is capable of lifting the
camera.
22. During the fill time, you should be straightening out the blimp’s stays, positioning
the blimp strings, tying the ribbons to the stays (do not make knots!), and
generally making sure that the blimp’s mechanics look functional.
23. Once the blimp is full, tie the kite string to the blimp feeder string. We’ve
attached the string to the blimp with knots, then have duck-taped the entire
connection for safety.
24. Before moving the blimp, be sure to attach it to your body in some way! The blue
clamp strap works well cinched onto the kite winder handle then knotted onto a
belt loop.
25. Now get the camera ready.
Digital Camera Information
In order to collect aerial imagery, you need a digital camera that has either a “continuous
shooting” mode or time lapse capability. This changes over the years, but the Canon
Powershot has long had this capability, so this is the camera referred to in this protocol.
Three of the Canon Powershot models we have used are the SD900, SD990, and S110, of
which the SD990 was the best.
26. The settings for the Canon Powershot should be flash on, manual, continuous, and
ISO400. Be sure the battery is fully charged and that the memory card is empty.
Make sure that the maximum resolution is being used. For a 16 GB card, that
should yield ~2400 potential pictures. If the camera says there are 9999 pictures
remaining, it tells you the resolution is too low.
27. Attach the camera to the blimp once the settings are confirmed.
28. The last thing before launching the blimp is to set up the open shutter on the
camera. Saving this for the final step will save you a bunch of pictures.
29. Use the device sent with the blimp for holding down the shutter. Use two rubber
bands to secure it to the camera. Make sure the camera is clicking away as you
loft the blimp.
30. To empty blimp, open the two release valves and gently assist pushing helium out
of the blimp. Blimp needs to be completely empty before wrapping it into the
tarp. Detach the short stay as before from its ribbons and fold it along the other
stay for ease of transport.
Blimp Flight Guidelines
1. FAA regulations only permit a maximum flight height of 500’, but the blimp
often goes at an angle, so the spool has up to 1000’ of string. The string is colored
so that every 50’ has a different color, which allows you to track how much you
have let out.
2. How high up you go depends on how wide the channel is and what resolution you
are aiming for. ~250’ seems like an ideal balance, but if the channel is too wide,
then you might have to go up to the full 500’, but the closer to the ground the
clearer the pictures. As cameras increase in resolution, then this is less of a
problem.
3. The best approach to using the blimp is to go right up to the maximum height of
500’ and do a run along the river at that height. Then drop down to the preferred
height and do another run at that height to get the maximum resolution with
reasonable coverage.
4. Depending upon wind conditions, it may take lots of blimp manipulation (more or
less height via the kite string), walking, or boat maneuvering to get the shots
needed. Wind plays a big role in how much effort it takes to reel in the blimp.
5. If the blimp simply will not go up, then that tells you there is an air inversion
taking place. This usually happens when hotter air gets trapped under cooler air,
which we have seen several times in canyons. The cooler air prevents the blimp
from rising. There is no solution other than to hold off until the next morning or
when conditions change.
Notes on blimp/camera
1. You will be able to see the flash flashing, so you should be able to tell if the
camera is still taking pictures. I’ve tried the ‘no flash’ setting and it uses up the
memory card space in less than five minutes – not good.
2. Typically I have the blimp lofted for 30-60 minutes per deployment. Just keep
looking for the flashes and as long as that is going, then you know you are good.
3. The camera takes pictures every 5-20 s, slowing down over time. It helps to
count out so you know to steady up when a photo is about to be taken.
4. The most tedious part of the deployment is reeling in the blimp. It is also the
hardest part if it’s windy.
5. Did I mention to always have the blimp tied down? We don’t want to lose it!
6. If it is windy, you may want to weigh down the tiles with a rock so they don’t
blow off of their GPS location.
7. It’s easy to re-deploy the camera again and again once the tiles are in place.
8. Recharge the camera battery between deployments!! The one battery will run out
of power more quickly than our desire to get more pictures. Plug the battery and
recharge unit into the inverter as soon as you have downloaded the pictures and
erased them from the memory card.
9. Use the time in between deployments to have a good look at the latest pictures.
Use knowledge from previous deployments to figure out where you might need to
walk/boat to get pictures of other needed areas.
Blimp deployment
Field Check List
laptop computer, fully charged
computer power cord
waterproof computer case
camera
camera battery, fully charged
camera manual
USB cord from camera to computer
camera battery recharger
shutter hold-down used for deployment
tarp
kite-blimp wrapped inside tarp
numeric tiles, wooden
linoleum tiles, all
Items in white bucket:
blue clamp strap
two green clamp straps
two rubber tie-downs
duct tape
thread tape for pressure regulator
wrench to tighten pressure regulator
kite string and winder
rubber bands
zip-ties
repair kit for blimp
tape measure
two pairs of gloves
extra ziplock bags
first aid safety manuals
boating rules
extra rope at bottom of bucket
sponge
GPS case
GPS data logger
GPS antenna
GPS antenna pole (two pieces taken apart will fit into bottom of case)
GPS batteries(4), fully charged
12v battery, fully charged
power inverter
pressure regulator
air hose from tank to blimp (inside pressure regulator box)
two helium tanks, with safety tops
hedge clippers
caliper
swiss army knife
First Aid kit
life jackets
towel to shade computer, if needed
clipboard
data sheets
pencils/pens/sharpie
50
17
21
25
29
32
35
38
41
43
45
47
48
49
50
50
650
222
275
325
373
418
460
498
532
563
589
611
628
640
648
650
Angle (•)
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
Angle (•)
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
700
239
296
350
402
450
495
536
573
606
634
658
676
689
697
700
100
34
42
50
57
64
71
77
82
87
91
94
97
98
100
100
750
257
317
375
430
482
530
575
614
650
680
705
724
739
747
750
150
51
63
75
86
96
106
115
123
130
136
141
145
148
149
150
800
274
338
400
459
514
566
613
655
693
725
752
773
788
797
800
200
68
85
100
115
129
141
153
164
173
181
188
193
197
199
200
850
291
359
425
488
546
601
651
696
736
770
799
821
837
847
850
250
86
106
125
143
161
177
192
205
217
227
235
241
246
249
250
900
308
380
450
516
579
636
689
737
779
816
846
869
886
897
900
950
325
401
475
545
611
672
728
778
823
861
893
918
936
946
950
Length of Spool out (ft)
300
350
103
120
127
148
150
175
172
201
193
225
212
247
230
268
246
287
260
303
272
317
282
329
290
338
295
345
299
349
300
350
400
137
169
200
229
257
283
306
328
346
363
376
386
394
398
400
500
171
211
250
287
321
354
383
410
433
453
470
483
492
498
500
550
188
232
275
315
354
389
421
451
476
498
517
531
542
548
550
600
205
254
300
344
386
424
460
491
520
544
564
580
591
598
600
Use this table to determine the height at which
the blimp is flying. The table assumes that
there is no slack in the line. Remember to add
the height from the ground to the position of
the clinometer.
450
154
190
225
258
289
318
345
369
390
408
423
435
443
448
450
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