Satellites have increasingly been used to monitor suspected human-rights abuses in recent years, but cost still is an obstacle: a single high-resolution image can cost as much as $10,000.

Bromley says the potency of satellite imagery increases when it meshes with other technologies. Mobile phone and web-based "crowdsourcing" platforms like Ushahidi (www.ushahidi.com) make it possible to create a dynamic and interactive crisis map to help flesh out the information in a satellite snapshot.

"The magic happens when you start pulling all these things together and you use them as an array of tools to understand what's going on. The more you understand what's going on, the more likely you are to influence the policy decisions," Bromley explained.

Still, satellite images seldom convey the legal or moral nuances of a conflict. In the case of Sri Lanka, for example, the U.N. experts' report accuses Tamil Tiger rebels of taking refuge in designated safe zones - effectively using the civilians there as human shields, and shooting them if they attempted to escape.

Bromley says it is also difficult for satellites to capture the moves of a guerrilla force like the Tamil Tigers. "They would just kind of run out with a mortar tube and fire a few shots,” he said. “And run back into a shelter. That kind of stuff doesn't appear on a satellite image at all."

As a result, a single image may at times give a misleading view of what has happened on the ground.