A Review of the DJI GS Pro App: Part 1

In what  is probably the first comprehensive review and field test of DJI’s new waypoint and mapping app – DJI GS Pro – I cover the app’s features and functions in detail. In the next post, I outline a series of field tests using a Phantom 4, and include sample orthomosiacs and 3D models.

At the start of the year, DJI released a completely new version of their Ground Station app – DJI GS Pro. The original Ground Station app dates back to 2013, long before the DJI GO app and tablet-based drone interfaces appeared. It was designed for plotting and uploading waypoint flight plans to early versions of the Phantom, as well as for DJI aircraft using the Naza-M and WooKong-M flight controllers.

With the the introduction of the Inspire 1 and the DJI GO app back in 2015, the company started migrating key telemetry, video, and flight control systems to the now-familiar tablet / smart device interface. Both the GO app and the hardware have come a long way since. The GO app now includes waypoint, point of interest, follow me, active track, a slew of camera controls and settings, and many more features.

The original Ground Station App (which only worked via a Bluetooth connection) was looking somewhat redundant!

However, DJI has clearly been watching the growing number of sophisticated third party waypoint apps that have appeared in the last couple of years. Principal among these is Litchi, which has built a reputation as a full-featured waypoint and flight planning system, including such features as panorama, VR mode, and a sophisticated range of options.

Land Mapping

There’s also been a proliferation in the number of third party waypoint apps focused on land mapping, photogrammetry and orthomosaics. Key among these are DroneDeploy, Map Pilot (from MapsMadeEasy), SkyCatch, Altizure, and PiX4Dcapture.

All of these apps are designed to work in conjunction with their respective map image processing engines, which nowadays are pretty much entirely cloud-based: that is, drone-captured image sets are uploaded to a cloud service, where they’re processed into orthomosaic maps (and 3D models if desired), distortion free and topographically corrected to fit the landscape of the site surveyed.

Finished maps can be viewed and shared online, or downloaded in a range of formats for further analysis and processing. PiX4D does of course have a range of established desktop software applications for map processing and generation – principal among these being PiX4Dmapper Pro – but even they now offer a cloud-based subscription service.

Business Sense

Why so many land mapping apps? Because they’re useful. Really useful.

Drone mapping is proving cost-effective and fast when it comes to gathering important, timely data across a number of professions, including agriculture, environmental analysis, urban planning, architecture, construction, surveying, project management, and even insurance.

While mapping with drones offers solid business benefits and time savings across these industries, it’s clearly also a rapidly growing business opportunity for drone manufacturers and drone service providers.

DJI has obviously been watching this market growth with keen interest, and decided its time to get in on the game. Hence DJI GS Pro: an entirely new app, developed from the ground up to provide waypoint planning and execution using DJI drones in a number of different ways.

DJI GS Pro Functions

The new DJI GS Pro has three core modes or functions:

Waypoint

Up to 99 waypoints can be tapped out in the app, and – similar to Litchi – a range of actions and parameters can be set for each waypoint, including altitude, aircraft rotation, gimbal pitch, hover, start or stop recording, and image capture.

Virtual Fence

Virtual fence defines a specific flight area and boundary. Useful in scenarios where a flight needs to be carefully restricted into one area, such as  manual pesticide spraying in agriculture, or if the aircraft needs to be kept away from a restricted or no-fly areas.

I can also see a use for this function in structural inspection situations, especially power line inspection. Setting a virtual fence at a set safe distance away from a power line tower would be preferable to relying on the aircraft’s object avoidance systems, which could easily be fooled.

DJI says its also useful in pilot training situations, staying within the defined flight area. However, I would have thought beginner mode in the DJI GO app provides more or less the same function.

3D Map

What has been useful, and what continues to be in demand, is the land mapping capability. It is this that I’m going to look at in more detail, because in short, DJI GS Pro is a serious competitor to the existing third party mapping apps, and gives them all a run for their money (so to speak).

Similar to other apps, the area to be mapped is tapped out and adjusted to fit, then various parameters are set, including aircraft altitude, front and side overlap of photos, gimbal pitch, and so on.

DJI calls this mode ‘3D Mapping’ and while its true that reasonably detailed 3D models can be generated from a set of core map images (i.e. just images shot straight down at 90 degrees), DJI is also set to include a 3D POI (Point of Interest) mode, designed for shooting images and capturing structures from all sides.

Its just not there yet… this POI mode is yet to be implemented, and right now its flagged as an “Optional extra. Coming soon” on their website, so its not clear right now how effective this additional feature will be.

DJI GS Pro: The Mapping Interface

Also note that right now, GS Pro appears to be available only on iOS and is iPad only – no Android (Google Play) version at the present time, and no iPhone compatibility. That could prove to be an issue for Mavic owners.

On launch, the interface is straightforward, well designed and pretty intuitive. The app launches with your standard satellite map in the main part of screen, a dark grey data bar along the top, and a white ‘saved mission’ list down the left side. Tapping the tiny arrow icon slides the mission list away into the left edge, freeing more space for the map.

The data bar along the top carries icons for:

  • Home button (return to main screen)
  • Aircraft connected icon (will also show P4, I1, etc. when connected)
  • Current app mode (Waypoint, Virtual Fence, or 3D Map)
  • Number of GPS satellites, and signal strength
  • Controller-to-aircraft signal strength
  • Camera connected (name of camera and signal strength)
  • Aircraft battery level (showing both battery percentage and voltage level, which is nice)
  • iPad battery level (a nice feature – even the GO app doesn’t have this!)
  • Settings menu (via the same 3-dot icon used in the GO app)
  • And finally, the flight execute or start button (changes to a big red pause button when the mission is in progress)
Main screen of the new DJI GS Pro app during a mission, showing top data bar, mapped area in blue, take off point (green ‘H’), aircraft in flight (white dot with blue arrow), aircraft telemetry (lower left), and camera view (lower right)

Immediately below the data bar, to the right are:

  • Show / hide waypoint paths switch (just hides the paths, not the perimeter of the area to be mapped)
  • Current location target button (assuming your iPad is connected the internet, tapping this will zoom the map to your current location)
  • Satellite view / map view / hybrid view toggle switch
  • Map rotation lock / unlock switch (by default its off, with the map locked to North at the top, but can be turned off during flight, so the map follows the view of the iPad)

To create a new mapping mission, simply tap the blue ‘New Mission’ button, lower right, and select the desired type of mission from the icons. In this case, we’re focused on ‘3D Map’. After selecting ‘3D Map’, you can select either ‘Tap’ to tap out a new map area on the underlying map, or select ‘Aircraft’ and – assuming your aircraft is airborne – fly to desired positions overhead and select those as perimeter points for your map.

Assuming you select ‘Tap’ to create a new map prior to flying your drone, the background map will zoom to your current location (if not there already) and you simply tap anywhere on screen to start your new map.

The Mission data panel that appears when you create a new map.

As soon as you do this, you’ll get a small blue translucent square with selection handles at each corner, very similar to those found in other mapping apps. You’ll also see a white data panel slide out from the right, containing information on your map, and a number of parameters you can adjust, sorted into ‘Basic’ and ‘Advanced’.

Drag the corner handles of your map square to adjust its shape and size to fit the area to be mapped. Small ‘+’ handles in between can be dragged to create more points around the shape. To delete a point or handle, tap on it to select it (it turns blue with a white border), and tap the trash can icon at the bottom of the white data panel.

For greater flexibility, you can create map shapes with indents and concave perimeters – useful if there are structures within your mapped area that you don’t need to appear in the map for some reason. This is a feature not available in most of the third party apps: DroneDeploy’s app can do it, but Map Pilot cannot, and in PiX4Dcapture, you can only create square or rectangular map areas.

As you adjust your survey area to fit, information towards the top of the right hand data panel updates with overall flight time (estimated), flight length (distance to be flown), and number of waypoints within the mapped area.

There’s also a box called ‘Mission Type’ with the title “3DMap – Area”, but strangely, there’s no calculation or indication of the area being mapped.

This seems like an odd omission, as it’s useful to know how much area you’re intending to cover, whether that be in hectares, acres, square metres, etc. Its also odd, because its a feature available in almost all the third party apps. Hopefully it will be added in a future update.

Below these data boxes area a number of adjustable parameters, divided into Basic and Advanced. Under Basic you have:

  • Camera Model – this will update automatically if you’re connected to your aircraft, but if not, its worth setting this correct camera early, as this can affect the field of view.
  • Shooting Angle – the choices are ‘Parallel to Main Path’ or ‘Vertical to Main Path’. All these seem to affect is whether your aircraft flies forward down one leg and backwards down the next leg, or sideways to the right down one leg, then sideways to the left down the next leg. Unlike most of the other mapping apps, GS Pro doesn’t turn the aircraft at the end of each leg so that it’s flying forwards every time.
  • Capture Mode – here you can choose from ‘Capture at Equal Dist. Interval’, ‘Capture at Equal Time Interval’, and ‘Hover&Capture at Point’.
    • For the first two, the aircraft is continually moving while photos are taken at equal distances apart (the normal mapping method), or at equal timed intervals. For equal timed intervals, I wasn’t able to test this on my Phantom 4, as the app threw an error message saying timed interval wasn’t supported on the P4 – not sure why.
    • The third method, ‘Hover&Capture at Point’ stops the aircraft above each capture point, shoots the photo, then moves on to the next point. This lengthens the flight time considerably, but I’ve found it does result in better maps. Not necessarily sharper images, but more precisely geotagged images, because the geotagging happens while the aircraft is stationary, not while its moving. I’ve found another result is much better 3D model renderings of sites when using this method.
    • Previously, the only other app I found that used this hover&capture method was PiX4Dcapture, so its nice to see it implemented in GS Pro.
  • Flight Course Mode – here the choices are ‘Scan Mode’ and ‘Inside Mode’, and only refers to how the flight plan handles concave or indented parts of your map. If you have a map with an indent – say a structure or building you don’t want included in the final map, but you still need the areas around it – you can have the aircraft fly over the part you don’t need: in ‘Scan Mode’ it won’t capture images, and will just carry on mapping once it hits the other side of the indent. Or in ‘Inside Mode’ the aircraft will stop at the indent boundary, turn and go down the next leg, and basically not fly over the indented area at all, sticking closely to the boundaries of your map. ‘Scan Mode’ can be more efficient in terms of flight time, but if you’re trying to avoid a very tall structure, ‘Inside Mode’ might be more appropriate.
The Advanced tab settings

Below these settings are sliders for adjusting speed, and altitude (and hence image resolution in centimetres per pixel). And below these is a nice little toggle panel for adjusting each point on your map in precise Lat and Long steps, down to 6 decimal places – a nice feature if you’re trying to map a very precise area, perhaps to match up with a previously done map.

Under the Advanced tab, you have slider settings for:

  • Front Overlap Ratio – overlap percent of photographs
  • Side Overlap Ratio – overlap percent of photographs
  • Course Angle – adjusts the angle of the paths within the defined mapped area
  • Margin – this allows you to adjust the end waypoints inside the mapped area to create a margin around the boundary of your area, which could be useful in some instances.
  • Gimbal Pitch Angle – again, another nice feature to have, that I’ve only seen before in PiX4Dcapture. Most of the time, you’d want the gimbal pitch to be 90 degrees, i.e. pointing straight down. But there may be applications where a different pitch angle would be more suitable – say a large hillside site. Also, I suspect gimbal pitch angle is also here as part of the yet-to-be-implemented POI function.
  • End-Mission Action – here the choices are
    • Hover – the aircraft will just stay at the last point. You can take over and fly it back manually
    • Land – land directly below the final point of the map
    • Return to Home – self explanatory, but you need to set your RTH altitude in the GO app beforehand.

Once you’re all set and your mission is saved, you tap the Airplane icon (upper right), and a nice Prepare for Flight dialogue panel appears with a list of pre-mission checks to make sure everything is in order. At the bottom, you’ll see the waypoints being uploaded to the aircraft: once done, the ‘Start to Fly’ button at the bottom becomes active, and you’re ready to fly.

So, I took my trusty Phantom 4 out into the field and did some flight tests in 3D Map mode with the new app. How did it perform? You can read all about that, plus view actual maps and 3D models in the next article.

 

 

 

 

 

This useful checklist appears one you tap the airplane icon and are ready to fly.

Nick Foxall
February 2017

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