geologic formations in northern iraq

The accidental discovery of a new way to produce accurate elevation surveys from satellite photos

By Gerry Mitchell, P.Geo, President, PhotoSat

geologic formations in northern iraq

3D WorldView-2 image looking along dipping geologic formations in Northern Iraq. Produced by PhotoSat.

 

In an effort to find a faster way to produce elevation surveys from satellite photos, PhotoSat geophysicist Michael Ehling and I accidentally discovered a novel way to greatly improve the accuracy and resolution of satellite topographic survey results.

It was 2007, during the peak of the natural resource boom and PhotoSat could not keep up with the demand from Vancouver mining companies who needed accurate satellite survey data for their projects in remote parts of the globe. Without accurate ground surface surveys the mining engineers couldn’t produce reports of ore body volumes. Without the engineering reports the companies couldn’t report their mining discoveries to a booming stock market waiting expectantly for their news.

Interactive photogrammetric processes

Michael and I had been watching how photogrammeters produced elevation surveys from stereo satellite photos since 2004, when stereo IKONOS satellite photos first became available. PhotoSat was buying stereo IKONOS satellite photos from Space Imaging, now part of DigitalGlobe.

We were reformatting the photos so that the photogrammeters could produce elevation surveys using computer systems that had been designed for processing stereo photos taken from airplanes. They were using highly interactive processes and were taking an average of 150 hours to produce satellite surveys for 100 square kilometer projects.

Automatic matching

Michael and I could see that the processors spent most of their time interactively measuring the matches between identical features on pairs of satellite photos. The photos had been taken with the satellite looking at the same area on the ground from different directions. By identifying identical ground features on each of the photos, and precisely measuring their locations, the elevations of the features can be computed.

When Michael and I asked if the photo feature matching could be done automatically we were told that the automatic process usually didn’t work, but when it did, editing the results took more time than doing the matching interactively, so no one used it. As geophysicists we were intrigued by what looked like an interesting technical challenge.

Oil and gas seismic processing tool box

In the 1980’s and 90’s when I was working as a Geophysicist in oil and gas exploration I processed a lot of seismic data. Oil and gas seismic survey data is used to image geological formations thousands of meters below ground in the search for oil and gas. Seismic data processing has always been one of the most complex and computer intensive data processing fields, with expenditures of billions of dollars annually.

Over the past 50 years seismic processors have developed an immense array of data processing tools, including many automatic image matching tools, and I thought that we could probably apply these to the satellite photos.

Gerry and Michael at the siesmic workstation

Oil and Gas seismic processing and interpretation workstation. Gerry Mitchell on the left and Michael Ehling on the right. This technology was the inspiration for the PhotoSat satellite processing system.

Michael tested seismic processing image matching tools on stereo IKONOS satellite photos for several months in 2007. He had to format the digital satellite photos so that they would look like seismic data to the seismic processing systems, run tests, and then reformat the results to look like photos again.

We were in search of a faster way to produce the survey results that the photogrammeters were spending hundreds of hours to produce. We were testing with a pair of IKONOS satellite photos that had already been processed by the photogrammeters so that we could compare our results with theirs.

Gerry, Michael and Jayda at workstation

Michael, Jayda and Gerry using the PhotoSat Workstation on a satellite surveying project.

 

Initial PhotoSat processing test results were amazing

After three months of testing we had our first real success. We were astounded by the results. We could see many fine topographic details on our test data that were simply not visible at all in the photogrammetric processing.

We continued to refine the process over the next few months until we had produced satellite survey results that were over three times as accurate as the photogrammetric processing and had much more topographic detail. The initial process took over 100 hours of computer processing time to process 100 square kilometers, so we had not really found a faster way to produce the results, but completely unexpectedly, we had found a way to produce better results.

comparision of photosat survey

Satellite survey of a river valley processed by conventional photogrammetric methods on the left and by PhotoSat processing on the right. The PhotoSat surveying shows fine topographic detail on the river flood plain that has no expression on the conventional processing.

New PhotoSat Workstation built from scratch

Now, nine years after our initial accidental discovery we still have a team of researchers and software engineers improving our satellite processing system.

Several years ago they replaced the seismic processing system with a computer system built from scratch to efficiently apply the seismic algorithms and processes to satellite photos. This system, the PhotoSat Workstation, was designed to harness the processing power and speed of Graphics Processing Units (GPUs). The GPUs process numerical data a thousand times faster than CPUs. Older software that is retrofitted to use GPUs typically shows speed improvements of two to five times.

It took several years and several million dollars of software development, but since our initial discovery in 2007 we have successfully created an automatic process that produces satellite surveys much faster than the photogrammeters, with much higher accuracy and better topographic detail.

 

 

 

 

 

Suncor mature fine tailings

Canadian Mining Association Adopts New Tailings Recommendations

The Canadian Mining Association has agreed to implement a new set of guidelines aimed at improving tailings storage practices. In the wake of the Mount Polley incident, Canada’s principal mining industry group has agreed to adopt a raft of new waste management policies.

Tailings have been in the news recently following several major spillages, and the industry is responding by tightening up codes of practice to ensure better waste management becomes the norm.

Following Mount Polley, when mining waste was accidentally released into Canadian lakes and rivers, an independent review was commissioned by the B.C. government. The Chief Inspector of Mines weighed in, finding that geological features under the dam including a layer of clay weren’t taken into account at the design stage. The CIM found that while mining operations there didn’t break any laws or regulations, they didn’t meet best practices either. In response, the Energy and Mines Minister Bill Bennet announced in 2014, the government planned new regulations that would make British Columbia a world leader in tailings storage.

The government-commissioned review, completed in January last year, recommended that all mining companies operating in the region should abide by the MAC’s code of best practice: in response the MAC organized its own independent review, seeking to improve that code.

The raft of 29 recommendations will extend tailings policy in both directions – up and in, to the heart of mining companies with tailings ponds or storage, and out to the communities nearby. MAC chief executive officer Pierre Gratton said in December, ‘Everyone of these recommendations, if it’s going to reduce the incidents, we want to implement as quickly as possible.’

Communities who may be affected by tailings incidents are to be involved in accident response planning and training, reflecting increased recognition within the industry of local communities as stakeholders in the industry. Meanwhile responsibility for signing off on tailings measures will be taken into the C-suite, effectively making the core of the company responsible for tailings.

Other measures recommended by the government review include the phased introduction of Best available Technologies, an increased role for tailings review boards and expanded corporate design commitments.

Satellite Surveying for Improved Tailings Monitoring

PhotoSat has extensive experience mapping tailings areas to help improve monitoring and management. We have been providing 20cm accuracy satellite surveying for Suncor’s Millennium Mine about twice a month since 2013, after they compared our mapping to alternative methods. The engineers at Suncor use our elevation data (DEM) for most of the mapping and surveying of their Tailings Reduction Operation. They also use it to help reduce their Mature Fine Tailings inventory.

Satellite ortho photo and PhotoSat elevation image of Suncor’s mature fine tailings

Suncor mature fine tailings

© DigitalGlobe 2014

 

In addition, Golder Associates uses our elevation models for satellite monitoring of the Penasquito Tailings Storage Facility. They presented their results at the Tailings & Mine Waste Conference in Vancouver in October 2015.

To find out more about using our high accuracy elevation models for tailings operations, contact us at info@photosat.ca, or 604-681-9770.

 

Seismic survey points

Improve Seismic Survey Planning with Highly Accurate Elevation Models

When planning a seismic survey, petroleum engineers need to know which seismic source points can be accessed safely by vibroseis trucks. Using high detail elevation models generated from satellite imagery, PhotoSat can help.

We use elevation surveying to prepare the groundwork for seismic surveying. Before holes are drilled or vibroseis trucks are on the move, planners know where the likely best spots are. And thanks to PhotoSat’s 30cm accuracy elevation models, they also know where trucks can’t go.

Overturning vibroseis trucks on steep or sudden inclines is a real risk. Planners need more than contour lines: they need high resolution, accurate topographical data to allow them to plan how to best use their vibroseis equipment while keeping their trucks and crews safe. Mapping the ground slope to within 30cm elevation accuracy enables mapping of no-go zones that are too steep for vibrator truck operations, lowering the risk of overturning the vibes on steep inclines. Our clients tell us that this improvement in seismic survey planning helps them reduce project costs and saves time.

Seismic survey points

 

Advance scouting is expensive, risky and time-consuming. And it comes under fire for its environmental impact. PhotoSat’s proprietary geophysical processing system allows us to create usable digital elevation models and precision satellite images within just a few days of a satellite acquisition, with 30cm elevation accuracy and with no boots – or tires – on the ground. The resultant data can then be used for subsequent project engineering and design.

Another advantage of having accurate survey data in the early project stages is the ability to use the elevation models for quality control of the seismic shot and receiver point survey data. In addition, the data is engineering-quality and can be used for all future design and construction work. This reduces survey wait times and allows managers to have increased faith in the reliability of the data.

So how do we get these kinds of accuracies? We have developed our own unique process, and more information can be found on the Technology page. Also, we have published numerous Proof of Accuracy Reports, that compare our elevation data to tens of thousands of independent survey points.

If you’d like to learn more about how PhotoSat built software developed for seismic data processing into a powerful, fast and accurate satellite surveying tool, or find out how that tool can help your project happen, contact us at info@photosat.ca or 1-604-681-9770.

PhotoSat 3d elevation image

Comparison to LiDAR verifies accuracy of WorldView-3 satellite elevation mapping to within 15cm

Back in March this year, we were proud to announce that we’d verified the accuracy of DigitalGlobe’s WorldView-3 (WV3) satellite topography. The digital terrain model PhotoSat produced from DigitalGlobe’s WorldView-3 stereo satellite data was found to be accurate to within 15cm in elevation. Of course, that meant our customers could look forward to unprecedented accuracy from us, with an accuracy study to back it up. Here’s the original piece from PRNewswire:

 3d elevation image

PhotoSat 3d elevation image from WorldView-3 satellite data of the Garlock Fault in California

Engineers to benefit from high quality elevation products

VANCOUVER, March 25, 2015 /PRNewswire/ – PhotoSat is pleased to announce that the elevation data processed from DigitalGlobe’s new 30 centimeter resolution satellite, WorldView-3, has been verified as accurate to within 15 centimeters. DigitalGlobe is a leading global provider of commercial high-resolution earth imagery products and services, and is the first company to offer 30 cm resolution satellite imagery commercially.

For the study, PhotoSat produced a 50 cm grid of elevations using its proprietary geophysical processing technology with stereo satellite images taken by WorldView-3. The resulting elevations were then compared to a 50 cm LiDAR elevation grid in Southeast California, accurate to approximately 5 cm in elevation and available on the OpenTopography website. The size of the comparison area was 88 square kilometers. The resulting 15 cm RMSE elevation accuracy was impressively achieved using a single ground reference point. The full WorldView-3 accuracy study is available on the PhotoSat website at www.photosat.ca/pdf/garlock-30cm-wv3-elevation-accuracy-report-mar2015.pdf.

PhotoSat’s highly accurate elevation grids have been used for years by oil and gas and mining engineers as a cost-effective alternative to ground surveying and airborne LiDAR mapping. The satellite imagery from WorldView-3 will allow PhotoSat to deliver the highest quality topographic data yet.

“The DigitalGlobe WorldView-3 satellite data is the highest quality satellite photo data that PhotoSat has ever processed,” said Gerry Mitchell, President of PhotoSat. “In this test, an elevation grid extracted from stereo WorldView-3 satellite photos matches a highly accurate LiDAR elevation grid to better than 15 cm in elevation. This result takes satellite elevation mapping into the engineering design and construction markets and directly competes with LiDAR and high resolution air photo mapping for applications like flood plain monitoring.”

“The fact that PhotoSat has validated our elevation data to within 15 cm is amazing and even exceeds our initial expectations,” saidKenyon Waugh, DigitalGlobe’s senior director of vertical segment products. “With these elevation products, customers in the oil, gas, and mining sectors can leverage our truly global reach and realize cost savings on the order of 50 percent.”

LiDAR and satellite elevation data

LiDAR grid compared to PhotoSat’s WV3 grid. Comparison of the LiDAR and WV3 elevation grids for a 1000m wide area. Minor differences between the elevation grids are visible.

 

About PhotoSat

PhotoSat has invented a new technology that generates the world’s most accurate satellite topographic mapping.  This engineering quality data shortens timelines and eliminates surveying delays in all phases of resource and engineering projects. We have delivered over 500 highly accurate elevation mapping projects, and have published a number of accuracy studies which are available on our website. For more information please visit www.photosat.ca.

About DigitalGlobe

DigitalGlobe is a leading provider of commercial high-resolution earth observation and advanced geospatial solutions that help decision makers better understand our changing planet in order to save lives, resources and time. Sourced from the world’s leading constellation, our imagery solutions deliver unmatched coverage and capacity to meet our customers’ most demanding mission requirements. For more information, visit www.digitalglobe.com.

To find out more, either visit us at  www.photosat.ca, view the original accuracy report here or contact us at info@photosat.ca.

Accelerate Mining Volume Measurements with Satellite Topography

Accurate mine planning requires continually adjusting the plans for the situation on – and underneath – the ground. Resource quantities and locations are changing frequently, and mine layout is affected by blasting, tunneling and ore removal. That’s especially true in open pit mines, but all mining engineers face the difficulty of working with the same digital elevation data while the ground shifts.

In fact, that’s one problem that more efficient communication between the mine face and site and the engineer simply can’t solve, because no one on the ground has a high-level overview either. What’s needed is an update of the original elevation data to reflect what’s happened since.

A common method of doing this is with LiDAR (Light Detection and Ranging). But LiDAR is expensive and time consuming, so we need a mapping system that can be used more often. The only snag is that it has to both deliver similar accuracy and cost significantly less to permit more frequent use.

Step forward satellite topography.

Satellite topography using new, geophysical processing techniques results in similar accuracies to LiDAR and can be used for yearly, quarterly or monthly reconciliations, allowing engineers to work with accurate representations of what’s really happening on the ground. PhotoSat’s satellite elevation mapping for mining volumes has proven accuracies of better than 30cm, providing a clearer picture.

Mining volume changes over an open pit

Volume changes over an open pit mine

 

That means that when it’s time to make volumetric change measurements in pits, stockpiles, waste dumps and tailings, satellite mapping lets you view and analyze the situation simply and easily. Our clients tell us that one of the main advantages of using our satellite system is the ease with which they can check on as-built locations of buildings and structures and reconcile them to the original plan. Reconciliation can even be on a biweekly basis if the project is moving fast. That helps engineers with tailings management, and also makes life easier and safer for on-the-ground surveyors, resulting in greater accuracy and fewer injuries.

How can a satellite system deliver biweekly updates? Partly because after ground-based scans have been acquired, the images have to be compiled. In the case of a system like vehicle-mounted ILRIS (Intelligent Laser Ranging and Imaging) that’s the bottleneck; from raw data to point cloud to the computer processing and satellite location necessary to produce a useable image, nothing much can compete with the 8 days PhotoSat’s technology can take to produce a useable result.

Satellite image with mining volumes

Satellite photo with mining volume changes

 

Finally, using satellites rather than ground-based methods removes the need for surveying to take place on or near the mine site. As a result, the surveying process is safe and never needs to interfere with mine operations. There’s no risk of damage to vehicles or injury to surveying personnel when your imaging is done from space!

To find out more about how satellite topographic mapping can help make mining a safer and more efficient process, leave us a comment or contact us at info@photosat.ca.