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Weather is a big driver of how good the resulting maps will be. Because of lens limits and the requirement for high shutter speeds to reduce motion blur, maps are best when taken with bright light. The best results are around noon when the sun is directly overhead and casting few shadows; a bright, overcast day also works well for similar reasons.
When ambient light is low due to heavy clouds or in the evenings, the camera will expose the scene but will have to increase ISO to get reasonable exposure. Beyond ISO 1000, noise and blur from the denoising filter in the camera will start to impact photo quality.
If light conditions are low, the shutter speed can be reduced. However, the drone will need to fly slower to ensure no motion blur. The camera lens is sharpest above f/5. Some lens artifacts and blurring around the edges may be present with a wider aperture/lower f-stop.
Additionally, flying over wet surfaces may cause problems for photogrammetry workflows. It tends to make asphalt very dark, which can cause stitching software to have a hard time, and reflective surfaces can't be used to stitch photos.
AMC caches recent maps. To make certain that maps for a specific location are stored on your controller before you go to a site with no internet, download them while the Pilot Pro tablet is connected to wifi.
Tap the Arrow icon in the top-left corner of AMC, select Settings, and select Offline Maps. Select "Add New Set".
Offline maps gather satellite data from the selected source (in this case, Bing Hybrid maps) and download tiles to make up the map in up to two different zoom levels. The higher the zoom level, the better the quality of the image and the more tiles it will take to cover the area framed by your screen.
As such, high zoom levels of large areas can lead to very large file sizes. Lower zoom levels are recommended for large areas, and higher zoom levels will result in better offline maps for smaller areas. After adjusting the map to your preferences, you can select Download.
After the map is downloaded, you can view it from the Offline Maps page. Any missions in the area on this map will show the satellite images even if you are not connected to the internet, and if the "Fetch elevation data" option was selected you will also have the option to view the terrain height while planning your mission.
DIU Blue Astros come with stealth logging enabled, which stops GPS data from being written to imagery and logs. Stealth logging must be disabled to allow GPS data to be written to photos
1. Figure out the minimum safe flying altitude at your site (i.e. above obstacles and giving a good line of sight). Enter this value in AMC > Vehicle Setup > Safety > Return Altitude.
2. Open AMC Plan view, and select "Pattern" in the left sidebar (creates flight path that covers the site and automatically triggers photos). Choose a pattern type and shape and it'll appear on the map. Don't detail the shape yet- We'll come back to that.
3. In the Pattern/Survey waypoint settings, open the Camera tab, and select Preset: Sony ILX LR1 - 24 mm (or whichever lens you are using)
4. Set Altitude. Start in Pattern waypoint settings and enter the minimum safe value from step 1. Check the Ground Sample Distance (GSD) value at the bottom of Pattern Waypoint settings. If GSD is smaller than your needs, increase altitude to increase GSD. Then go to Mission Waypoint settings and enter the same altitude.
5. Turn on Terrain Display by selecting the square T button in the bottom-left corner. Check the heightmap to make sure the flight path clears the terrain by a comfortable margin.
6. Set speed. Check the Photo Interval value at the bottom of Survey settings along the right. This interval needs to be 2 seconds or more. If it's less, decrease the mission flight speed or increase forward overlap (if this is acceptable for your mission). If the photo interval is larger than 2 seconds, you can optionally increase your flight speed.
Terrain follow can also be enabled, though it should be used cautiously; terrain data is not guaranteed to be accurate, and it does not take into account any obstacles such as trees.
7. Set speed. Check the Photo Interval value at the bottom of Survey settings along the right. This interval needs to be 2 seconds or more. If it's less, decrease the mission flight speed or increase forward overlap (if this is acceptable for your mission). If the photo interval is larger than 2 seconds, you can optionally increase your flight speed.
8. Adjust the Pattern area. Make sure the green area (the area to be flown and photographed) is larger than the map you need. Make the green area larger on every side by at least the width between flight passes. Note the estimated flight duration at the top of the screen. If the duration is longer than 23 minutes, it's likely to require a second flight.
9. Add a Return waypoint command if you want the aircraft to come home and land when finished. This is optional but recommended. If the mission's last command is a Pattern or Waypoint, AMC will not notify you that the mission has ended. The aircraft will hover at the last waypoint, likely until the battery failsafe is triggered and Astro returns home automatically.
If these instructions are unclear or if you have any additional questions, you can learn more about planning in the AMC docs or contact us at support@freeflysystems.com.
To get high-quality results, every area of interest in the map should appear in 5 or 6 overlapping photos. Obtaining this much coverage along edges or in corners requires that the area to be flown is larger than the area to be mapped. Also consider that if the gimbal is not pointing straight down (for crosshatch surveys and such), the drone will need to fly PAST areas that need to be seen in images because the image is looking in front of the drone.
The USB flash drive included will be formatted to work with Astro. In the event that you encounter issues or would like to use a different USB flash drive with Astro, follow the instructions in the USB Formatting section. Be sure enough space is available; you will need at least 16GB for a single mission.
The Astro + LR1 kit and the LR1 Payload both include a Samsung 64GB flash drive. If you want to replace or purchase additional flash drives, we recommend trying to get the same model as we have tested this drive thoroughly. It will also help our support team troubleshoot any issues you might encounter.
Lens Aperture ring: A
Lens Focus switch: AF
Focus: Auto (we don't recommend infinity focus on Astro 1.6.14 FW)
Exposure Mode: Manual
ISO: Auto
Aperture: f/5 - f/11 depending on lighting conditions
Shutter: 1/1000 or greater (can go as low as 1/500 but aircraft needs to slow down to prevent blur)
Storage: USB Drive
When light is low (e.g. dark cloudy day), we need to adjust the shutter speed and aperture to avoid an excessive increase in the ISO sensitivity. The first step is to open the aperture. If an aperture of f/5 is still not bright enough, the second step is to decrease shutter speed. Working in this order keeps shutter speed as high as possible to minimize motion blur. If shutter speed must be reduced and motion blur is seen, reduce flight speed.
Astro + LR1 Payload is designed to fill the needs of enterprise mapping and inspection workflows.
Learn more about the
The LR1 Payload consists of a Freefly gimbal with an integrated Sony ILX - LR1 camera. It is developed for use with Astro and other vehicles that use the Freefly Smart Dovetail and the Pixhawk Payload Bus standard.
The LR1 Payload uses the Astro Isolator. Info on how to install the isolator on Astro is here:
More info on the isolator system for Astro is here:
Smart Dovetail is not hotswap compatible. To avoid damaging Astro or your payload, please power off the aircraft before attaching or removing a Smart Dovetail payload.
To install the gimbal:
Power off the aircraft.
Orient the gimbal under the aircraft so that it is facing forward and the Smart dovetail is facing upwards.
Slide the gimbal Smart Dovetail into the Isolated Dovetail receiver that is on the underside of the aircraft. Slide until you hear an audible click of the safety latch and the connector is fully seated.
Close the dovetail locking lever until tight and the gimbal is secure.
To remove the gimbal:
Power off the aircraft.
Open the dovetail locking lever so that it is loose.
Hold the safety latch so that it is disengaged.
Slide the gimbal dovetail towards the front of the aircraft to fully disengage from the Smart Dovetail Mount and remove the gimbal.
LR1 Payload is compatible with: - Astro firmware 1.6 and above. - AMC 1.28.10 and above
LR1 Payload Output Specification
The standard workflow for mapping with Astro takes photos from the camera, geotags them, and writes them to the attached USB stick. The usb stick will contain data from each flight in separate folders.
Photos can be saved to either SD card or USB drive. When photos are saved to the SD card, no geotag is applied. However, all other files will be written to USB drive if one is connected.
Naming: <SequentialFlightNumber>_<DATE>_<TIME>
There may be multiple folders that start with the same <SequentialFlightNumber>
if photos were taken on the ground but without a flight.
Each folder will contain the following:
This file contains the GNSS observations from the aircraft's RTK GPS, and is used in conjunction with the base station data to precisely locate the Astro in space. The file also includes RTKlib-style "marker" entries at the timestamp when each photo was taken
This JSON formatted file includes the precise timestamp and gimbal angle for each photo captured.
This JSON formatted file includes the aircraft position, attitude, timestamp, and capture url for each photo taken.
Name: YYYY-MM-DD-[SequentialNumber matching directory].json
File type: JPG
Naming: per camera settings
Geotags: Each photo is geotagged in its EXIF header, including geographic position and altitude in WGS84 (GPS) coordinate frame. The altitude in the aircraft geotags is based on the EGM96 geoid.
Note that additional tag information may be written later when post processed by a PPK app.
This folder contains small 512x341 thumbnails of the photos taken. They are geotagged as well, and are sometimes useful to upload to a photo photogrammetry site such as ESRI Sitescan to ensure that photos are geotagged as expected. They can even be used to create a quick, coarse map.
The LR1 Payload was primary designed for photography applications (mapping, inspection, scenic photography), but can shoot video as well.
The camera is capable of shooting up to 4K, 60 fps footage in 8 bit or 10 bit, with normal and Slog profiles
A V90 Class SD card is needed for some recording modes. The LR1 Payload ships with a V60 Class SD card which is fast enough for 4K30 fps 8 bit footage.
The External USB drive isn't fast enough to record high quality video, so videos will save the camera's SD card.
You can switch between taking images and video footage using this button in Photo Mode:
The Sony ILX-LR1 can get very hot when recording video, especially high frame rate and high bitrate footage. If the camera gets too hot, it will shutdown!
We recommend flying in 'Slow mode' for smooth/precise yawing motions with the gimbal. Setting the vertical/horizontal speeds to max is speeds as Position mode, but allows precise control over the yaw rate of the aircraft. This is particularly useful for longer lenses
We have been getting good video results with the Sigma 24mm, Sony 35mm lenses, and Sony 50mm. The Samyang 75mm can sometimes have issues with stability during acceleration and deceleration.
If you are seeing any vibrations in the footage, check:
You are using the right vibration isolator
The gimbal is balanced properly
AMC provides control of these settings in flight by pressing the icon on the right of the screen while in Photo Mode:
Choose a survey flight path angle that minimizes the number of turns (or in other words, think about maximizing long, straight flight paths). For example, if surveying a complex next to a road that runs at a 30-degree angle, rotating the survey lines to match may reduce the maneuvering Astro has to do and will result in shorter missions and better pictures.
Rotate the survey entry/exit points to start and end at logical places. It is usually more efficient and safe to start at the furthest point from your takeoff location, as your mission will likely end closer to the home point when battery levels are most critical.
Use overlap and sidelap settings suitable for your processing software and output type. AMC's defaults (70%) are reasonable starting places, but reducing these values can allow faster flight and more area coverage. Lower front overlaps will allow Astro to fly faster in a mission, but be sure the value is acceptable for whichever processing software is in use.
Astro + LR1 can cover areas greater than 1 km^2 (240 acres) in a single flight at 2cm GSD. Some tips for flying these types of missions:
Uncheck the "refly at 90°" option at the bottom of the Survey settings while planning a mission. This will cause Astro to only fly over the ground in single-direction passes as opposed to a cross-hatch pattern.
If possible, fly from the center of a large survey to reduce the distance between the remote controller and Astro. The maximum telemetry distance is shown in AMC during mission planning if you're at the takeoff location. Being able to have a line of sight to the vehicle at all parts of the survey is important for safety as well as maintaining a solid data link.
A "typical" large area survey might have the following parameters: 12m/s speed, 120m altitude, 70% front overlap, 65% side overlap, and the gimbal angle pointing down (90°).
Astro defaults to limiting the distance between waypoints to 900m. This is intended as a safety check to ensure that an accidental waypoint doesn't send the drone out of range to an unintended location. However, this may limit the length of a reasonable survey in some edge cases. This value can be increased by changing the parameter MIS_DIST_WPS. Do not set it larger than necessary to maintain the safety benefit.
Smaller areas can be covered the same as a large project, but usually higher detail is desired. In these cases, a crosshatch pattern can be used with gimbal pitch to get better detail on the sides of vertical objects. This gives better 3D reconstructions.
Check the "refly at 90°" option at the bottom of the Survey settings while planning a mission.
Set the gimbal angle to around 70 degrees to get better imagery on the sides of objects.
Fly lower (60m or less) depending on the situation. Lower altitude will result in higher-density photos; just make sure that safety is the highest priority and that no obstacles intersect with your flight path.
Make sure to fly well beyond the boundaries of the object being surveyed when the gimbal is tilted to ensure that it can be seen from all sides.
Generally speaking, slower flights will provide more accurate results.
The aircraft can hotswap batteries to allow for the continuation of a mission that requires more than one flight. To hotswap, do the following:
Disconnect one of the discharged flight batteries from Astro.
Replace the removed battery with a fully charged pack.
Press the power button on the battery twice and ensure it turns on and says "hotswap" on the new battery's LCD screen.
Disconnect the second discharged battery.
Replace the second removed battery with a second fully charged pack.
Power on the second battery the same way, and ensure both are powered up.
Continue mission after the post-processing for the previous flight has been completed and there is no longer a progress bar on the remote controller.
It's possible to plan missions and monitor flights from AMC on a computer or tablet. Here's the procedure to connect another device to the remote controller.
This is a set of example calibration values for the Sony ILX-LR1 with Sigma 24 mm lens, which can be used for photogrammetry initial conditions. Each lens is slightly different, but these values are good initial values if the software in use can't solve them directly.
The LR1 Payload can easily be configured to perform inspections on power lines, wind turbines, and other infrastructure!
For inspection use cases, we recommend using a long lens to maintain a safe distance from your subject. We have found that both the Sony FE 50mm F1.8 and Samyang 75mm F1.8 work well.
The Samyang 75mm may need a lens firmware update to work well in autofocus mode with the LR1
After changing the lens, make sure to balance the gimbal, covered in this section:
We recommend the following camera settings for sharp, detailed images:
All of these parameters can be setup in AMC, accessed by the 3 lines under the shutter button Additional settings we recommend:
Focus: Auto
Focus mode: Center or Zone
Overlay: Reticle
DIU Blue Astros come with stealth logging enabled, which stops GPS data from being written to imagery and logs. Stealth logging must be disabled to allow GPS data to be written to photos
Download the offline maps for the area you will be flying in
Check the vibration isolators are in good condition before each flight
Check the gimbal is balanced and the thumbscrews are tight
Astro is resistant to electromagnetic interference created by high voltage power lines with our Compassesless algorithm! Make sure Astro is updated to 1.6 or later
Pilots should still be careful when flying close wires and towers as these can often be difficult to see
Be careful when flying under structures! Astro can lose GPS signal and drift
Be careful when flying near wind turbines! Astro can fly in winds up to 12m/s (27mph), above this Astro will trigger RTL.
The current estimated windspeed is displayed in the lower right-hand corner of AMC in flight
Parameter | Value |
---|---|
Name | Setting Range | Explanation |
---|---|---|
Focal Length (mm)
24.351
Principle Point X (pixels)
4714.485
Principle Point Y (pixels)
3172.286
R1
-0.017
R2
0.071
R3
0.009
T1
0.001
T2
0
Shutter Speed
1/4000 to 1/100th
A faster shutter speed reduces motion blur
Aperture
F5 or higher
Higher the aperture makes more parts of the image in focus
ISO, White Balance
Auto
Auto for these usually work well
JPEG Size
Large
More detail = better!
Image Storage
External USB
Images are geotagged when saved to the external USB. This allows images to be associated with specific assets like power line poles
These free applications make it easy and simple to improve the accuracy of your survey through their use of Post Processed Kinematic corrections.
If you are not able to follow these steps exactly, there is more guidance below.
Set up your base station (list of tested stations are below) and get it recording
Fly your mission with Astro, then wait for it to finish processing photos after landing
Pull USB-C stick, and insert into iPad (if accessing base-station data from iPad)
Go to Files app, browse to USB drive, and determine which folder has the files from this scan. i.e. folder 58
If using EMLID REACH:
Open EMLID app:
Stop logging all 3 logs (position, raw data, base correction)
After they are zipped, download all 3 files to the usb stick in the same directory as the scan
Freefly PPK Desktop Application takes photos and GPS data generated by Astro during a Mapping mission, as well as data from a GNSS base station, and applies the Post-Processing Kinematics (PPK) algorithm to tag photos with highly accurate geotags.
Download the software from https://freeflysystems.com/support/astro-support
Current Version: v1.0.0-beta - Released 11/27/2023
Table of Contents:
Compatible Devices, Download Links
Input, Output, Workflow
Debugging tips if you encounter errors
Operating Systems
Note, for the current app version, you will need to override current mac security settings through instructions provided here: https://support.apple.com/en-us/HT202491
Trimble R2,10,12
Emlid RS2
Generally, any device that can output RINEX (Observation and Navigation data files)
Important Tip: PPK process and upload to mapping software is 10x faster if you have the files in your local storage instead of thumb drive
Output folder from High Res LR1 Payload.
RINEX files (OBS and Nav Data files) from GNSS base station (that was actively recording GNSS data for the full duration of the time that the Astro mission was running).
GNSS base station coordinate
Using pre-surveyed point as reference coordinate
Using Reference Network calculation (i.e. NOAA's CORS, Washington state's WSRN)
For very basic results, averaged value from base station rinex file
Photos in PPK_Photos folder with corrected geotags.
PRE-PPK CHECKS
As summarized above, to start PPK-ing your photos to get centimeter level geotag accuracy, you need to:
Complete an Astro mapping mission that writes photos, imagelog.json, *capture.obs, and *capture.json file into a mission folder (see Fig 1 below) into the USB-C thumb-drive.
Fig 1. Here is what the mission folder generated by Astro + LR1 might look like:
Have a GNSS base-station running and recording satellite data throughout the duration of the flight that can produce (Observation and Navigation data files). Grab the RINEX data files (usually ends with .<##>O - for OBS or .<##>P for NAV, sometimes just .RNX for both file types). If the file names are ambiguous, you can inspect the files and look at the first few lines to see if they contain the keywords Observation (for obs file) or Navigation (for nav file) data file. IMPORTANT - Ensure that the NAV data file is a "MIXED NAV" data file that contains nav data for all constellations.
Grab the Observation and Navigation data files (either individually) or the folder that contains them and place it into the Astro Map mission folder that contains the photos and the other mapping mission artifacts (imagelog.json, *capture.obs, and *capture.json).
Placing base station file into the folder shown below:
Fig 2. Placing base-station files into the folder shown above. The file types might be different
Pre-PPK Notes:
Do not close any pop-up cmd prompt or terminal windows (this is due to the application running a subprocess necessary for PPK-ing)
It's a good habit to check to ensure that the original geotags on a couple of the photos somewhat correspond to the image location.
To do this: Use an exif inspection tool, grab the geotag from an image, search up coordinates on Google Earth, compare to see if the photo content somewhat matches up with coordinates on Google earth
If the images do not align, it might be a good idea to get the flight log (.ulog) file from the mission and use the Use ULOG workflow in the Freefly PPK app to get proper alignment.
Freefly PPK Processing:
Open FreeflyPPK application.
Click on browse at the top to choose the Astro Map mission and select the folder.
The application should browse the folder and search for the requirements and automatically fill in all of the requirements.
4. If you know where the base station ground coordinate was, then enter it. This can be done using a GNSS reference network processing provider (i.e. in Washington state you can use Washington State Reference Network, in the U.S. you can use NOAA CORS and upload your base RINEX files) You can use either DMS or Decimal coordinates (Click the DMS Coordinates
check-box.)
5. If you don't know the base station coordinate, by changing from MANUAL
on the drop down to AVERAGE FROM OBS
you can get a very rough estimate of the base station. It applies single point positioning to the base station RINEX files. The averaged postion will be displayed on the status bar once the project processing begins.
6. Go ahead and select how high you placed the receiver from the ground (usually your base station tripod pole will have a marking to let you know). The application will take care of antenna phase center variation based on the base-station type detected from the base-station OBS file.
7. If you are rerunning the same mapping mission folder, checking the Overwrite Output check-box will overwrite the output folder with the current processing output. It is set to overwrite on default since the application can otherwise keep on making copy of the photos and take a lot of space on your computer. If the Overwrite Output check-box is not checked, then the application will rename the previous folder and save the output of the current processing to PPK_Photos.
If you want to explore output with multiple settings (i.e. different base station coordinates or base station files), it might be beneficial to rename the PPK_Photos folder to something more useful
8. Once all of the project requirements are met, you will be able to click the Process button and the application will correct the geotags on your photos after it conducts PPK on them. It will output them into the PPK_Photos folder and keep your original images untouched. Monitor the output and ensure all or most of the photos are tagged with Q=1 quality. The Q value corresponds to the quality of the corrected geotag. Q=1 is great. Q=2 is ok. Anything higher is not accurate.
9. Once your images are PPK-ed, you can use a map generation provider like ESRI Sitescan (which is recommended and we have tested on) and upload the images from the PPK_Photos folder. In the Advanced Processing Settings:
If you completed the PPK process with a surveyed point or reference network, use the +/- margin of error they provided to you in the base station location for the geolocation accuracy.
If you use the AVERAGE OBS FILE option in the FreeflyPPK app, use +/- 100 cm. Note that it is not recommended to run AVERAGE OBS if you want high fidelity maps.
Debugging Tips:
Known Issue: If drone is flying below sealevel or drone is flying at negative altitude in the chosen base-station coordinate system, then the application will fail the geotagging process (status list error). This will be fixed in a future release.
If you entered base station coordinates in Degrees, Minute, Second format, make sure you use the correct sign. i.e. If the coordinate you are entering is 122° 09' 7.93789" W, on Freefly PPK, you should enter -122 09 7.93789
If the correct base station file is not be detected correctly, remove all of the base files from inside of the project path folder. Then, individually go into modify the selected base and rinex files using the modify buttons below the status box. Check content inside the base files for "Observation" and "Navigation" to ensure you are choosing the correct files.
One of the first debugging things you can do is to close the application and reopen it. More advanced users can go in and delete the .ppk_history file in their home directory to remove application cache file.
Check to see if the rtkdata_events.pos in the working directory has been generated properly. If everything looks good there, but there is an issue with photo tagging. (i.e. "Issue with abc.jpg tagging" alert, then there is likely an error with your filesystems (see common file systems error).
Common file systems errors: Not enough space on your hard drive. Make sure the project path has plenty of space. A bunch of 25MB images can fill up your storage device quickly. Again, as previously mentioned, you will get much better performance if your project folder is in your local hard-drive instead of an external drive.
If you have any issues with Freefly PPK and have questions for Freefly Support team, it would help if you sent as many of your files as you are able to (i.e content of working directory, capture.obs, sequence.json, and base-directory folder). It helps to include a screenshot of the application during an error, but ensure you expand the status list so that the whole error is visible in the photo.
Precise Flight by Auterion is an alternative option for the PPK workflow. It can be downloaded from the App Store.
iOS devices - primarily useful with iPad
Set up base station and get it recording
Fly mission with astro, wait for it to finish processing photos after landing
Shutoff astro
Pull usb stick, and place into ipad
Go to files app, browse to usb stick, and determine which folder has the files from this scan. I.e. folder 58
Open emlid app
Stop logging all 3 logs (position, raw data, base correction)
After they are zipped
Download all 3 files to the usb stick in the same directory as the scan
Extract data
Go to files app
Browse to the folder with the photos in them
Click once on the zip file with the emlid raw RINEX data in it to unzip
It will create a folder in that directory
Delete old data
Go to preciseflight app
Select base station folder, will be the RINEX directory inside of the flight folder
Select the vehicle folder- it is the folder with your mission number such as “58” that has the photos in it
Decide if you want to set base position manually, enter as desired
Enable compensate camera offset
Hit process, wait the 30-60 seconds for processing
When processing is complete, the files will be located in the Auterion Precise Flight app on the ipad (not on the USB stick).
When working properly, Sitescan app can be pointed at that folder to upload the photos
Use the files app to copy the PPK’d photos into a new folder on the usb drive and then transferring to computer.