Instructions for collecting digital aerial photographs.
Note - these instructions are valid for the camera setup used on the SIPEX 2007 voyage. You may need to update them for future trips - or there may be a different camera altogether.
Reference sheets
Some useful information on shot interval timing and shutter speeds for different lenses, flight altitudes and speeds.
Pre-voyage
If you have a voyage coming up, take it to Walch optics for a service - 149 Macquarie St, 6223 8855.
Also, become familiar with Nikon's camera control pro, a software package used to control the camera while in flight.
Basic Nikon D1X setup - check for each flight
A few things to do before you strap the D1X into its bucket for flying...
- The camera must be in 'Shutter priority mode' which is indicated by an 'S' in the display on the top RHS of the camera, or in the information panel in camera control pro. Once airborne the shutter must be set as fast as possible without under exposing the image.
- The camera must be in manual focus mode. This is selected on the front of the camera on the opposite side to the shutter release. The correct setting is 'M' not 'S' or 'C'. The focus ring must be set to infinity and taped in place with a small piece of gaffa tape.
- On the top left of the camera the ring under the three buttons 'Bracket, Flash and ISO' must be set to 'S' indicating 'Single shot mode'. Press the little button just near the ring to enable this to be changed.
- The camera must be set up to receive GPS data. Press the Menu button and go to the Set Up Menu, scroll down to 'GPS Input' and use the button selector to ensure that this is selected. This should only need to be set once and left for the entire voyage.
- Image numbering should be sequential for the entire voyage.
- check that the camera clock is set to GMT+00:00:00. This will save several large headaches in the future!
About the bucket...
The camera is bolted into a removable bucket for flight via its tripod mount and a bracket inside the flight bucket. Once it is bolted in, it is only really practical to change camera settings using camera control pro.
- Make sure the camera has a fresh battery when you bolt it into the bucket. Take a spare, fully charged battery with you.
- You need to attach the power cable, firewire cable and 9-pin remote cable to the camera before mounting it in the camera bucket. Connect the cables and double-check that they are secure, then bolt the camera into the bucket.
- After bolting the camera in, open the bucket shutter and clean the lens. The 14mm lens is a tight fit, and sometimes scrapes little foam bits off as it goes in. Once the lens is cleaned, close the bucket shutter tightly.
- Mount the bucket assembly into the floor hole of the aircraft. Make sure you always mount the camera the same way - for example, viewfinder toward aircraft centre. Chaos will ensue if you don't stick to a single camera orientation
- Check again that all cables are plugged in securely.
- Make sure the allen key for the camera bolt is secured.
- If you have a long delay between mounting the camera and taking off, check the lens again before you fly, an remove any dust or spots that have settled on it
Pre-flight startup
These steps take place inside the helicopter. It is painful to get in and out, but once you're in you have some room to maneuver.
- Prior to takeoff, ensure that all cables are securely connected.
- The laptop may be switched on at any point - but leave the camera power off until the INS is on and communicating.
- When the camera is on, start camera control pro and check that the software can detect the camera. If it can't, first check the cables, then turn the camera off and on again. Restarting the camera will normally start communication.
- Check that the intervalometer is connected, and working.
Once you take off...
- Once in the air, do some yoga and open the shutter.
- Before you put the trapdoor over the camera, peek down through the camera to check that the camera has a clear view, and check that the camera back display shows that the camera is on. YOu'll see a count of the flash card capacity - note the number and keep an eye on it if the camera stops communicating with the PC.
- Double check that the camera and PC are talking. If they are not, it is yoga time - reach down into the bucket and restart the camera. This usually sets things right. Any time that the camera and PC are not communicating, images are transferred to the camera's internal CF card, and are named using a different scheme. This is OK, but makes life a bit tricky later on.
- Put the trapdoor on the bucket. This is another tricky yoga pose in polar boots and an immersion suit, but well worth it since you can then relax and put your feet anywhere.
All systems go, camera rolling
- Look over the pilots shoulder and keep an eye on the airspeed, and if you're getting a GPS message input, the ground speed and altitude. Alternatively, talk to the pilot and ask them to update you if speed/altitude changes. Use this information to set your shot timing interval with the intervalometer. It is better to shoot too many images than too few, so aim for lots of overlap.
- Keep an eye on camera control pro to ensure that images are coming in. You should also pause the intervalometer and adjust settings if required in camera control pro.
- For low altitude radar or laser flights, the camera should be set to store JPEG images. You can set this in camera control pro, by choosing the 'storage'tab, and making a selection from the first drop down menu. For Fine JPEG, your shortest shot interval is about 3 seconds. If you need to shoot faster to get overlapping images, choose a lower resolution JPEG storage mode.
- For high altitude photography flights, the images to be stored are high resolution TIFF images. Again, choose your options in camera control pro.
- Note on shot timing: the helicopter can fly at a significant cross-track drift or crab-angle, particularly at low speed or on very windy days. This has the effect of reducing the along-track coverage of images! Keep tabs on the drift conditions [ask the pilot], and tighten up your shot intervals appropriately to ensure good swath coverage. Excess data is better - in general, keep the camera clicking as fast as possible!
- Keep copious notes in the aircraft. Any time the aircraft changes heading or altitude make sure this is recorded. Record the time, position and image number every time you need to make any adjustments. If there is useful information coming over the radio about what else is going on with the other aircraft record this too. Cross reference as much information as you can about the camera and aircraft operations. Too much information is barely enough. But if nothing else, record image numbers and waypoint information when you change direction! Enough information to compile a table like the one following will be invaluable for later analysis.
- Keep an eye on all connecting cables - they may vibrate loose.
- Enjoy the view!
| flight alpha, 20 september 2007 | |
| event | image number |
| leave ship | 1008 |
| start NW track | 1012 |
| arrive waypoint 1, end NW track | 1153 |
| depart waypoint 1, start E track | 1155 |
Coming in to land
- Wake up
- Start with some yoga - reach down, remove the trapdoor lid and close the camera bucket shutter.
- Pause the intervalometer
- Once you've landed and are ready to shut down the aircraft, power off the camera and PC.
- Go and drink copious amounts of coffee, remembering to take a quick nervous one before the next flight!
Postflight, and pre-next-flight
- Take the photo logging laptop from the aircraft as soon as possible and transfer all the images to a backup storage system.
- If images were stored in camera memory, download the iages from the flash card to the relevant flight location
- Clear images from the laptop hard drive, once you are sure you have copies of them!
- As soon as practicable, burn the images to DVD, noting the flight name, date, and image numbers on each disc.