Humming quietly, the flying robot hovers outside a highrise building.
The small craft, barely a metre across, works its way up to the 11th floor, examining the façade for such damage as chipped or crumbling concrete, defective joints and the like.
Keeping about two metres from the façade, the robot is on an inspection tour of the building.
It's equipped with a high-resolution digital camera that takes detailed images of each part of the building.
In this case, the work is being done in Saarbrücken, Germany, and the operator is Christian Eschmann, a researcher at the Franhofer Institute for Non-Destructive Testing.
His interest is in developing and adapting small helicopters for building inspections.
Many buildings and other structures in Germany were built after the end of the Second World War in 1945, and now their age is showing.
But, inspection can be difficult.
Sometimes cranes, platform vehicles or scaffolding have to be used — or small helicopters.
Eschmann said that a façade that's just 20 metres tall by 80 metres wide can take an engineer two to three days for a complete inspection.
But, the small chopper that Eschmann is demonstrating needs only three to four hours.
If there is concern about the state of the insulation, Echmann's machine can be equipped with a thermal imaging camera, which can provide images showing where heat loss is occurring.
And the inspector doesn't end up with just a handful of images. A flight of just 15 minutes can result in up to 1,200 photos.
Then, using a computer, the inspector can stitch together individual images to create an overall picture.
Eschmann is just one of many researchers, who are working in the field of construction robotics.
This can mean anything from a brick-laying robot to an autonomous machine that can enter such dangerous areas as nuclear containment domes, and use wireless communication to send information to a data collector outside.
They can inspect tunnels and the undersides of bridges.
They can climb the walls of storage tanks to check the integrity of welds.
They can climb the face of a hydro dam, conducting inspections that usually require engineers on swing stages.
And in Wales, an experiment is under way to use drone 'copters to check construction site waste.
In that one, drones take aerial images to create a catalogue of waste.
Then Arup, a design firm, will use BIM software to look at how design changes might affect the volume of waste.
The idea is to explore how the Welsh industry as a whole can reduce waste.
What has made all of this possible is the coming together of a number of technologies: miniaturization of helicopters, digital photography, reliable wireless communication and a growing sophistication of the sensors available.
And, in some cases, the availability of 3D printing.
Many firms make the small helicopters, usually with four, six or eight rotors, so the machines might be called quadcopters, if they have four rotors, or octocopters (eight rotors). One of the leaders is Saskatoon-based DraganFly.
Its four-rotor machines are used for industrial inspection, wildlife protection, aerial photography, 3D terrain mapping, agriculture, research, search and rescue, and public safety.
A number of police services in Canada and the United States fly Dragan machines, including both the RCMP and the Ontario Provincial Police.
The machines are small.
A couple of the models are just 71 centimetres in diameter and 25 cm tall.
They can be folded up and carried in a case, but can be set up and ready to fly in just a few minutes.
They are typically equipped with either a still camera or a video camera, although other equipment can be mounted when needed.
As the technology develops and is accepted by industry, the prices of these flying robots falls.
A start-up called DreamQii Robotis, based at Ryerson University in Toronto, is about to launch a line of drones, complete with a GPS system and camera.
It will be priced at about $1,200.
Drones, often called unmanned aerial vehicles, or UAVs, have some limitations attached to them.
To operate a UAV commercially in Canada you must have a Special Flight Operation Certificate (SFOC), issued by Transport Canada.
It specifies that UAVs can't be flown higher than 120 metres, for example, and must be operated within the line of sight of the pilot, or someone who is in contact with a pilot.
In 2011, Transport Canada issued 155 SFOCs. Last year it issued 945, indicating that the industry is still a tiny one, but growing.
In the U.S., regulators are writing a new set of rules for the operation of drones, and hope to have them in place by the end of the year.