Processing Survey3 Camera Images
The below information explains the best workflow to post-process images from the Survey3 cameras.
Capturing Images
The Survey3 camera will come with the best default settings that we expect to work for the majority of our customers, so there's a good chance you will not need to change them. It is not recommended to adjust any camera photo settings (shutter speed, ISO, white balance, etc) unless you know what you're doing and have our Reflectance Calibration Target. We have already set the default values so that you should not get over-exposed pixel values, but this likely makes the images darker than you are used to. Darker than normal images are fine for processing as it reduces the chances that a pixel would be over exposed, and thus lose that pixel data. If you have questions about adjusting the settings, feel free to reach out to us for help, but when in doubt just use the defaults.
You no longer need to manually set the camera time, simply connect the GPS receiver and wait for the GPS lock to correct for any time drift during use. If you are using the GPS receiver (recommended) then the time will update every time it gets a good lock.
Even if you are not planning on using the included GPS receiver for geo-tagging the images, we recommend you connect it when you first get the camera. With the camera powered on and the GPS installed walk around outside with the GPS receiver pointing upward (side opposite the adhesive) until you hear 6 beeps, signaling the camera has a good GPS lock. This lock will then update the time on the camera to GPS time. You can then remove the GPS receiver if you do not plan on using it.
The Survey3 cameras can be told to take a photo either by its default internal timer (intervalometer) or using an external PWM signal received via the HDMI port.
The time between the timer triggered shots is a total of the camera's Interval setting value plus the time it takes to save the image to the camera's memory card. When we say the fastest the JPG mode can be captured is every 1.5s, this time includes the default 0.5s Interval settings time plus about a second to save the image. It's rare that you'd want to increase the Interval time, unless you do indeed want to capture less images. The 1.5s is also the average the timer mode will trigger at, as it will vary depending on camera settings, SD card memory speed and internal camera processes.
For the most reliable triggering we highly recommend you use the internal timer, as using the PWM signal can produce issues with missed images due to many variables within the camera. For instance, the model of the SD card you use, and how quickly it can save the image can affect how quickly the camera is ready again to capture the next photo. The memory cards we sell are what we used to determine the fastest capture rates, so using slower cards (meaning any other brand or model card) will likely trigger slower. Triggering the camera faster than it can save the previous image will cause the camera not to be ready and thus you will miss that new image. You can use our camera flight calculator at the bottom of the page here to see the fastest that a camera has to be triggered in order to provide the overlap you require for your survey. Pay attention to the "Photo Interval" line towards the bottom.
If you are triggering the camera via PWM make sure to set the Interval setting to OFF.
The camera will default to saving images only as JPG. In order to capture larger contrast in your images, along with not having any white balance, 8-bit compression and gamma applied, we recommend changing to the RAW+JPG mode. Setting it to RAW+JPG mode takes longer for the camera to save the image, so the time between triggers will be longer. In our MAPIR Camera Control (MCC) application you can easily convert the RAW to TIFF as well as to JPGs if you require it.
Prepare Images in MAPIR Camera Control (MCC) Application
Once you capture your images you may want to prepare them prior to stitching them into a 2D orthomosaic image or generating a 3D model, that's where our MAPIR Camera Control (MCC) application is used.
If you captured the images in RAW+JPG mode, then the RAW will be converted to a TIFF during processing in MCC. During processing the full image metadata including the GPS capture location (if using the included GPS receiver) will be copied from the JPG to the TIFF.
If you provide a photo of our Reflectance Calibration Target then the images can also be calibrated for reflectance. The images will be calibrated with each pixel representing a percent reflectance value. You can also choose to convert the TIFF files to JPG if your orthomosaic software does not support TIFFs (such as DroneDeploy, MapsMadeEasy, etc).
Creating the Ortho-mosaic Map
An orthomosaic is a single stitched 2D map image containing the many individual photos taken during your survey.
The quality of the orthomosaic and other exports will vary based on the capabilities of the software used to create the project exports. It is highly recommended you use processing software that can use the geo-location (GPS) information contained in the images for the best results. The photogrammetry engine code that combines the images can vary from software to software, so depending on the survey area subject matter certain software may perform better than others. For example, homogenous agricultural fields of closed canopy row crops is much more difficult to stitch together because the images tend to look similar.
Photogrammetry programs use structure from motion (SfM) methods, and are commonly known as "point cloud" software. They are called this because they create 3D models of points, or matched pixels to produce the exports. Since these programs create a point cloud they can also output .obj, .mtl and .jpeg modeling files to be used in 3D model viewers like Sketchfab.
There are typically 2 options to process your survey images: cloud-based applications or desktop-based applications.
Cloud-based applications, such as our MAPIR Cloud allow you to easily upload your images and will then notify you when the processing is completed. These services vary in how they charge you but the majority have a minimum monthly fee around $100. They also vary in the final results you'll get from their services, and typically the more expensive "professional" packages provide more outputs with higher cost. MAPIR Cloud supports RAW image input, but make sure to convert any RAW images to JPGs prior to uploading to most other software platforms.
Popular desktop software that can be used includes MAPIR Camera Control, Pix4Dmapper, Agisoft Metashape and Simactive Correlator3D.
