1. Jia Huang
Software Engineer @ 3DRobotics
Building a Drone Imagery Service

2. @AutodeskForge
#ForgeDevCon

3. see the world from above

4. Site Scan

5. Site Scan
Survey Scan Inspect

6. Scan Results
5 minute flights
84 Photos
90 minute processing time

7. Survey Results

8. Site Scan Video
• https://www.youtube.com/watch?
v=6BTC1Zjo8Ic

9. Site Scan workflow

10. Site Scan workflow
• geotagging
• user controls
• prepare job
• user validation
• saves results
• render mesh
• take photos

11. Challenges for the 3DR Cloud
• each image is ~10MB
• up to 250 images per job
• soon <= 2000 images across multiple flights
in one job
• Mesh / ortho / point cloud results are ~100MB
to ~200MB

12. 3DR Cloud Architecture

13. 3DR Cloud API
▪ All written in Scala with the Akka libraries
▪ Why Akka?
▪ Lightweight
▪ Flexible
▪ Everything is a stream
▪ Why Couchbase?
▪ Blob data
▪ Add more boxes as needed
▪ NoSQL with SQL interface (n1ql)

14. User Service
▪ User Service keeps track of
▪ users
▪ groups
▪ permissioning
▪ Why Postgres?
▪ highly relational data
▪ use the right db for the job

15. Recap Service
▪ Actors encapsulate state and behavior
▪ Communicate exclusively through messages
▪ Uses Akka’s Actor system
▪ Supervisor & children
▪ Each child Recap actor keeps its own state
▪ Supervisor gets passed errors

16. Creating a Photoscene with Autodesk Recap

17. Actor Supervisor Pattern
▪ Children can crash without damaging the system
▪ Supervisors handle errors
import akka.actor.OneForOneStrategy
import akka.actor.SupervisorStrategy._
import scala.concurrent.duration._
override val supervisorStrategy =
OneForOneStrategy(maxNrOfRetries = 10,
withinTimeRange = 1 minute) {
case _: ArithmeticException => Resume
case _: NullPointerException => Restart
case _: IllegalArgumentException => Stop
case _: Exception => Escalate
}

18. Actor Scheduling Pattern
▪ Actors can schedule themselves for future actions
class RecapActor(…) extends Actor with …{
implicit val system = context.system
private var scheduledTask: Option[Cancellable] = None
def receive = {
case PollScene(…) =>
scheduledTask = scheduledTask match {
case None => Some(
context.system.scheduler.schedule(10 minutes,
10 minutes, self,
PollScene(…) ))
case Some(cancellable) => scheduledTask
}
}
}

19. Interfacing with Autodesk Recap
▪ Handles authentication, sending & receiving to Recap
▪ Returns a Scala PhotoSceneEntity
▪ Formats, photolist, photoscene status,
processing time, and any errors
▪ Reuploads photos during error states
▪ Built on top of Akka-requests-lib
▪ https://github.com/3drobotics/cloud-akka-request

20. • Depends on the integration type
• State machine? Akka Finite State Machine
Mixin
• Relational? Another Postgres backed service
• Blob data?
• Keep things decoupled
Architecting future integrations

21. Questions?
jia.huang@3dr.com
@3drobotics
@AutodeskForge
#ForgeDevCon