wv3 accuracy study with histogram

The spark that ignited the PhotoSat accuracy studies

wv3 accuracy study with histogram

2016 PhotoSat WorldView-3 satellite surveying accuracy study, Asmara, Eritrea.

“Everything that the last speaker just told you is wrong”.   This shocked me since I was the last speaker.  I was just rejoining the audience after my presentation at a satellite data distributors’ conference in San Diego in 2008.

I had given a presentation on PhotoSat’s experience using satellite photos for elevation mapping.  I had shown comparisons between PhotoSat stereo IKONOS satellite elevation mapping and hundreds of mining exploration drill  collar elevations.  Our results suggested an IKONOS mapping accuracy of better than 1.0m in elevation.

The speaker who followed me showed the published specifications of the IKONOS satellite.  He declared that this proved that the results I had just shown were impossible. Then he went on to talk about his own stereo IKONOS mapping results.  His results showed 5m to 10m in elevation mapping accuracy.

 

Looking for a way to unambiguously measure our accuracy

The speaker who challenged PhotoSat’s results in the San Diego meeting actually did us a huge favor.  Although it did not feel like that as I sat fuming in my chair.  His comments provided the motivation for me to find a way to prove we were right.  After this meeting we set about looking for a way to unambiguously demonstrate the accuracy of the PhotoSat stereo satellite elevation mapping.

 

Searching for a detailed, high quality, ground survey data set

We concluded that to prove our accuracy we needed to find a highly accurate ground survey data set covering hundreds of square kilometers. But where to find it?

About two months later, a light came on.  I realized that we might find the elevation survey data that we needed from a large, regional, mining exploration gravity survey.  The topographic surveys associated with mining exploration gravity surveys are among the most accurate and carefully checked topographic surveys in the world.

 

An old friend tells me about an existing ground survey data set

I phoned Kevin MacNabb, president of MWH Geo-Surveys International.  Kevin did gravity survey contracts for me when I was a geophysicist at BP.  I said “Kevin, I am looking for a large regional gravity survey with thousands of accurate topographic survey points.  I want to use the topographic survey data to measure the accuracy of PhotoSat’s stereo IKONOS satellite mapping.”

I added “it would be great if the data is in an area of sparse vegetation in a remote region of the world.  This way we can prove the accuracy of our stereo satellite topographic mapping and show that we can do this anywhere in the world.”

Kevin replied “how would 45,000 ground survey points covering over a thousand square kilometers just west of Asmara, Eritrea do?”  For us this was the perfect data set. Eritrea was a challenging place to work.  It had just emerged from a civil war.  A perfect place to be mapping from satellites. For a fuller description, click this link.

 

Eritrea differential GPS survey crew and equiptment

Asmara Project, Eritrea. MWH Geo-Surveys differential GPS survey crew and equipment. Over 45,000 ground points were surveyed between 2004 and 2008. The Magellan RTK base with a ProMarkTM 500 GPS rover are shown in this photo.

 

The Eritea ground survey data is owned by an existing PhotoSat customer

It turned out that Kevin’s customer for the Eritrea gravity survey, Sunridge Gold, was also a PhotoSat customer for stereo IKONOS mapping.  We negotiated the right to use the 45,000 ground survey points for accuracy studies.  In return, we did some additional stereo IKONOS mapping for the company.

 

PhotoSat’s first comprehensive accuracy study

We were immediately able to use 10,000 of the Eritrea ground survey points to measure the elevation accuracy of 200 km² of stereo IKONOS elevation grid.  PhotoSat had already produced this elevation grid for Sunridge Gold.  We measured the accuracy of the PhotoSat elevation grid as 48cm Root Mean Square Error (RMSE).  The full 2008 IKONOS Eritrea Accuracy study is available to review.

 

PhotoSat accuracy measurement and improvement

Since 2008, PhotoSat has been using the 45,000 Eritrea ground survey points as a test bed to measure accuracy improvements in the PhotoSat processing.  This gives us a quantitative measure of accuracy improvements.  We have shown the results in many conferences and published them.  If there are still disbelievers they are certainly not challenging us publicly.

 

Satellite companies start to provide stereo test data over the Eritrea site.

In 2009, two commercial high resolution satellite companies, GeoEye and DigitaGlobe, provided stereo satellite photos over the PhotoSat Eritrea test area.   The DigitalGlobe data was from the 50cm ground resolution WorldView-1 satellite launched in September 18, 2007.  The GeoEye data was from the 50cm ground resolution GeoEye-1 satellite launched on September 6, 2008.

PhotoSat published elevation mapping accuracy reports for both new satellite systems.  The stereo GeoEye-1 PhotoSat elevation grid had an accuracy of 31cm RMSE, determined by 8,893 ground survey points.  The stereo WorldView-1 PhotoSat elevation grid had an accuracy of 35cm RMSE, determined by over 15,000 ground survey points.

 

WorldView-2 joint DigitalGlobe and PhotoSat news release on Eritrea accuracy study

Soon after the commissioning of the WorldView-2 satellite in early 2010 DigitalGlobe asked PhotoSat to use its new processing system to conduct an accuracy study over the Eritrea test area using stereo WorldView-2 photos.  The PhotoSat Eritrea Accuracy study showed WorldView-2 accuracy of better than 30cm RMSE.  These results were issued on March 16, 2010.  The news release is available here.

 

With accuracy improvement PhotoSat mapping becomes PhotoSat surveying

Once the PhotoSat elevation grids achieved an accuracy of better than 30cm many of our customers began using them in place of ground surveying.  We consequently renamed our products that have accuracy better than 30cm to surveying products.

 

The Eritrea ground survey data set has been used for hundreds of PhotoSat accuracy tests and studies

Since PhotoSat first acquired the 45,000 ground survey points in Eritrea, we have used the data for hundreds of accuracy test and studies.

 

2016 PhotoSat Eritrea accuracy studies

In 2016, we used the current version of the PhotoSat Geophysical Processing System to process a full range a stereo satellite photos over the Eritrea test area.  Some of these results are published on our website on the links below.  The link names include the satellite name, the number of ground control points used in the processing and the RMSE accuracy.

 

WorldView-3, Eritrea, 21 GCP, RMSE 15cm

WorldView-2, Eritrea, 21 GCP, RMSE 14cm

WorldView-3, Eritrea, 2 GCP, RMSE 19cm

WorldView-2, Eritrea, 2 GCP, RMSE 19cm

WorldView-1, Eritrea, 21 GCP, RMSE 19cm

WorldView-1, Eritrea, 9 GCP, RMSE 23cm

Pleiades-1B, Eritrea, 74 GCP, RMSE 26cm

Pleiades-1B, Eritrea, 1 GCP, RMSE 28cm

Kompsat-3A, Eritrea, 11 GCP, RMSE 48cm

Kompsat-3A, Eritrea, 1 GCP, RMSE 53cm

ALOS PRISM, Eritrea, 3 GCP, RMSE 1.4m 

SPOT 7, Eritrea, 1 GCP, RMSE 1.4m

ALOS PRISM, Eritrea, 1 GCP, RMSE 2.4m 

 

If you would like more information on PhotoSat surveying you can visit the following links.

Satellite surveying

Mining Industry Applications

Oil and Gas Industry Applications

Case histories

PhotoSat ground control: Using existing ground survey data instead of clearing land mines

300km2 PhotoSat survey in Kurdistan showing existing lines of GPS survey points.

“It’s too dangerous to survey any of the ground targets”

“The survey crew says they can’t survey the ground targets because of land mines and unexploded shells. I think it’s because it’s 50 degrees Celsius (122 degrees Fahrenheit) over there and they don’t want to leave their air conditioned camp. Either way we just cannot get you surveys of any ground points,” said the Geophysical Operations Manager for a 3D seismic survey in Kurdistan in early 2012.

We needed ground survey control to ensure accuracy for the 3D seismic survey

What were we to do? The customer wanted a PhotoSat survey to plan a +$20M 3D seismic survey over a 300km2 area in Kurdistan. We already had the satellite photos but could not get survey coordinates for any ground features that we could identify on the photos.

To be of best use for the 3D seismic survey, the PhotoSat survey needed to be accurate to 30cm in elevation and 1m horizontal. However, without ground survey reference it would only be accurate to about 3m horizontally and vertically.

We had to find a way to use existing ground survey data

Our only option to produce an accurate PhotoSat survey was to figure out some way to use existing ground survey data.

The oil company already had seismic survey lines on a 5km by 5km grid covering the project area. Based on this data they had drilled an exploration oil well at a cost of more than $10M.

It was a discovery well. They had discovered a significant column of oil. Now they needed a 50m by 50m grid of seismic data covering the entire project to decide where to drill next.

Existing lines of GPS survey points every 25m

The oil company’s existing 5km by 5km grid of seismic lines had GPS survey points every 25m along the lines. These survey points were accurate to 10cm in x,y,z. The company provided us with this data.

Absolutely no sign of the seismic lines on the satellite photos

Initially we were hoping that we would be able to see the seismic lines on the satellite photos. We thought that we could use the survey points and some evidence of ground disturbance to accurately reference the satellite photos to the ground.

The satellite photos were already within 3m of their true position. We were sure that when we zoomed into the high resolution satellite photos we would see some ground disturbance along the seismic lines.

No luck there! Due to the arid, rocky conditions of the ground we could see absolutely no sign of the seismic lines on the satellite photos no matter how closely we looked.

Tried shifting the PhotoSat survey grid until it matched the ground survey points

We then attempted to match the elevation profiles along the seismic lines to the 1m PhotoSat survey grid. We chose areas where the seismic lines crossed each other at 90 degrees.

We tried shifting the PhotoSat survey grid in x,y,z until we got the best match between the seismic line elevation profiles and the PhotoSat survey grid at the line intersections.

Shifting and matching seemed to take forever

This shifting and matching seemed to take forever. We started by making an ArcGIS TIN from the PhotoSat survey grid. Next we intersected the TIN with a file of the survey points. Then we extracted the PhotoSat survey elevation at each survey point and compared the elevations.

We shifted the TIN and repeated the intersection and elevation extraction.  We did this over and over again. Finally we found the shifts with the best horizontal and vertical matches between the survey data sets where the seismic lines crossed.

This was a painfully tedious, slow process. That is, until we thought about the alternative – clearing land mines and unexploded shells to get new survey points.

Established ten ground control points at seismic line intersections

Eventually, at each of ten seismic line intersections we located the best horizontal and vertical matches between the PhotoSat survey and the seismic survey data. At all of these ten points the surveys seemed to match to within 25cm horizontally and 10cm vertically.

Adjusted the entire PhotoSat survey grid to match the ground control points

With these ten ground control points we were then able to adjust the entire PhotoSat survey grid. We were hoping we had produced a PhotoSat survey grid accurate to better than 50cm horizontally and 30cm vertically.

North South scatter plot of the elevation differences between +5,000 ground GPS survey points and the 1m PhotoSat survey grid. The standard deviation of the elevation differences is 28cm.

Achieved an overall match to the +5,000 GPS survey points of 28cm

When we compared elevations of the 1m PhotoSat survey grid to the elevations of all of the points along all of the seismic survey lines there was a match of 28cm RMSE.

After this first PhotoSat survey project in Kurdistan in 2012, we surveyed several other Kurdistan projects over the next three years. We encountered the same situation in each project, and solved them all the same way.

We eventually developed a process to find the best matches automatically.  This has now become our standard method on all advanced projects with existing ground survey data. We no longer need to incur the time and costs of surveying ground features that can be seen on the satellite photos.

More details of our current process are available by clicking here.

Looking for more information on PhotoSat surveys?

 Advanced projects with existing ground survey data

 Guidelines for Stereo Satellite Ground Control Targets

Satellite surveying accuracy studies

PhotoSat Technology

 

 

 

 

3D satellite photo showing some of the 775 ground survey points

PhotoSat publishes 21 new satellite surveying accuracy studies

3D satellite photo showing some of the 775 ground survey points

3D WorldView-2 satellite photo of Asmara, Eritrea, showing some of the 775 ground survey points that determine the 14cm PhotoSat surveying accuracy.

21 PhotoSat surveying accuracy studies from seven different stereo satellites

PhotoSat has published 21 new satellite surveying and mapping accuracy studies, now available on our website. The studies include data from seven different stereo satellite systems. The best results show elevation surveying accuracies of better than 15cm.

The accuracy studies include stereo satellite data from the following satellites:

  • WorldView-1
  • WorldView-2
  • WorldView-3
  • Pleiades-1B
  • KOMPSAT-3A
  • SPOT-7
  • ALOS PRISM

 

PhotoSat has measured accuracy on over 750 stereo satellite surveying projects

PhotoSat has delivered over 750 satellite surveying projects since 2007 and we have carried out accuracy evaluations on the majority of them. Most of the survey data on these projects belongs to our customers and cannot be shared publically; however, customers have provided feedback on many of these projects.

The results of these 21 new accuracy studies are consistent with our project accuracy evaluations and customer feedback.

 

PhotoSat accuracy test areas in Eritrea and California

The accuracy studies were conducted over two test areas. One test area is west of Asmara, Eritrea where PhotoSat has access to more than 45,000 ground survey points over a 50km by 20km block.

The second area is in SE California where PhotoSat uses a very accurate Opentopography.org open source LiDAR survey.

 

The effect of different numbers of ground survey points

The studies employed different numbers of ground survey control points for each test area and each satellite system. For some of the satellite stereo pairs the accuracy is significantly improved by increasing the number of ground survey control points.

For example, the WorldView-2 survey for Eritrea is accurate to 19cm in elevation with two ground control survey points, and accurate to 14cm in elevation with 21 ground control points.

In contrast, the accuracy of the WorldView-3 survey for the California test area is not improved by additional ground survey points. This WorldView-3 survey is accurate to 13cm in elevation with one ground survey control point and with 153 ground survey control points.

 

PhotoSat has been continuously producing satellite accuracy studies since 2007

In order to provide objective quantifiable accuracy data for stereo satellite surveying and mapping, PhotoSat has been continuously producing accuracy studies since 2007. We have previously published nine of these studies. The rest of the studies were used for calibrating and improving our processes.

 

21 new accuracy studies all processed with the same version of the PhotoSat processing system

The 21 new accuracy studies were produced with the most recent version (2016) of the PhotoSat processing system. Where possible we used satellite data produced by the 2015 or 2016 versions of the satellite operators’ ground processing systems.

 

Summary of PhotoSat 2016 accuracy study results

Satellite Test area km² GCP RMSE
WorldView-3 California 150 1 13cm
WorldView-3 California 146 153 13cm
WorldView-3 Eritrea 100 21 15cm
WorldView-2 California 173 1 15cm
WorldView-2 California 173 153 12cm
WorldView-2 Eritrea 100 21 14cm
WorldView-1 California 174 153 14cm
WorldView-3 Eritrea 198 2 19cm
WorldView-2 Eritrea 400 2 19cm
WorldView-1 Eritrea 100 21 19cm
WorldView-1 California 174 1 23cm
WorldView-1 Eritrea 420 9 23cm
Kompsat-3A California 144 14 21cm
Pleiades-1B Eritrea 189 74 26cm
Pleiades-1B Eritrea 189 1 28cm
Kompsat-3A California 144 1 50cm
Kompsat-3A Eritrea 130 11 48cm
Kompsat-3A Eritrea 130 1 53cm
SPOT 7 Eritrea 1,458 1 4m
ALOS PRISM Eritrea 2,300 3 2m
ALOS PRISM Eritrea 2,300 1 4m

See PhotoSat’s accuracy studies overview for full details.

For more information about PhotSat’s surveying accuracy, please see our satellite surveying case histories or visit the following links.

Satellite surveying

PhotoSat 1m elevation image of a tailings beach, with 15cm vertical accuracy

The Challenge of Mine Tailings Beaches and Elevation Mapping

Mine tailings beaches are notoriously difficult to monitor. They’re the hardest surveying task at a mine. Data needs to be up to date, but tailings ponds can be huge: Suncor’s tailings ponds cover over 30 square kilometers. Ground survey teams can’t get close enough for safety reasons, and aerial LiDAR data delivery can be frustratingly slow. Low-flying drones are challenged by cold weather, and cannot cover much distance in a day, so are not reliable when measurements are required for a larger area on the same day.

That’s the challenge Suncor faced at its Alberta oil sands mine. Surveying Suncor’s Tailings Reduction Operation (TRO) site meant getting accurate data quickly over a mine site covering over 270 square kilometers. And when Suncor tried using traditional GPS, they found that only about 20% of the site was safe for crews to access. The next step was to try 3D laser scanners, but these simply couldn’t produce enough data fast enough; multiple set-ups were required and yielded sparse data that required significant processing to be comprehensible and usable. This meant adding to an already too-long wait time, as well as additional expense.

Elevation mapping solutions

PhotoSat’s 15cm accuracy satellite topography (DEM) addresses the challenge. Because we use high accuracy satellites, the data is collected safely and easily, reducing the need for ground crews to expose themselves to hazards. And we can collect satellite photos anywhere in the world, making them ideal for remote or challenging terrain.

50cm satellite ortho photo

50cm resolution satellite ortho photo of a tailings beach. © DigitalGlobe 2013

 

PhotoSat elevation image of a tailings beach

PhotoSat 1m elevation image of a tailings beach, with 15cm vertical accuracy

 

Once the satellite imagery has been acquired, we run it through our unique processing system, developed for the industry by us from seismic data processing tools, with engineers in mind.

We have proven the accuracy of our elevation mapping using tens of thousands of ground control points as comparison. Numerous proof of accuracy studies are available on our website.

We map the entire Suncor site every two weeks, providing usable elevation surveys only five days after data acquisition for use in Suncor’s bi-weekly engineering meetings. Our satellite mapping provides an instantaneous snapshot of the entire tailings beach waterline, the geometry of the beaches, and the height of the tailings dykes. We continue to map the Suncor Millennium and Steepbank mines every two weeks, including mapping the Mature Fine Tailings cells in thickness increments of 15cm.

The digital elevation models are also used for mapping windrows, monitoring tailings dykes, calculating volume changes, and verifying the locations of as-built infrastructure. When Suncor’s tailings engineers need to make a decision, they have the reliable, up-to-date data to base it on.

The original presentation made my Suncor at the 2014 Trimble conference that compares PhotoSat mapping to alternatives, can be viewed here.

To learn more or get a quote for topographic mapping for your resource project, contact us at info@photosat.ca or 1-604-681-9770.

satellite photo of a tailings beach.

Improving Safety for Mine Survey Teams: How Ground Surveying Fits Seamlessly With Satellite Topography

Mine survey teams perform a job that’s increasingly vital, increasingly technological – and more dangerous every day. When they’re doing preliminary work to acquire geophysical data for exploratory purposes, or scouting out pit placement, they’re subject to dangers including rockfalls and environmental dangers that can include severe weather and wild animals. Many mine sites are in inaccessible locations, in rugged terrain far from habitation, where it’s hard to put teams and even harder to get them out again fast when someone gets hurt.

At the same time, the industry is expanding into new regions where mining has previously been carried out with pick and shovel or even literally by hand. In sometimes socially-volatile places where old mine workings don’t show up on maps that are often themselves inaccurate, mine survey teams are saving the lives of miners by supplying engineers with accurate data – but they’re endangering their own safety to do it.

And what about when ground survey teams visit a working open mine to check for bench integrity? They’re sharing their working environment with heavy trucks and putting themselves in the way of slumping bench walls and falling debris.

PhotoSat’s 30cm accuracy satellite topography can provide a solution by filling in part of the puzzle. Mine survey teams will always be needed, but their exposure to risk should be minimized. When you get your elevation data from LiDAR or GPS, it can be significantly slower than PhotoSat’s unique geophysical processing technology. You’ll typically wait weeks, especially for aerial LiDAR. PhotoSat usually provides a client with engineering quality elevation mapping within 5 days, and there’s no boots on the ground so safety risks are minimized.

That doesn’t mean ground survey teams, LiDAR or other scanning technologies are redundant. Just look here to see how one of our clients, Suncor, combines multiple scanning technologies to get the data they need.  In 2014, Suncor and PhotoSat presented on the benefits of incorporating satellite surveying into their survey process for their Tailings Reduction Operation (TRO). With many areas of the TRO cells inaccessible to ground surveyors, the satellite-based technology reduced exposure to hazards.

But it does mean there’s a way to get a fast, engineering quality mine survey that can be used for multiple engineering and planning applications – without putting anyone in harm’s way.

To find out more about PhotoSat’s 30cm accuracy satellite topography for mine surveys, contact us at info@photosat.ca or 604-681-9770.

satellite photo of a tailings beach.

High resolution satellite photo of a tailings beach.

elevation image of a tailings beach

PhotoSat elevation image of a tailings beach

Toes and crests, satellite image

Automatic toes & crests mapping at Suncor’s oil sands mine

In this article we’ll look at how the engineers at Suncor have adopted our toes and crests mapping as an integral part of their mine planning process. This is the last post in a 3 part Suncor case study series. In the first post, we discussed Suncor’s comparison of various survey methods, and in the second article we showed how they use satellite elevation mapping for monitoring mature fine tailings.

Mapping of toes and crests is important for monitoring open-pit mining. On the ground, vehicular access, overburden removal and bench integrity needs to be ascertained if the mine is to continue to be profitable and safe. But on the ground is the worst place for surveyors to be: survey teams that examine mine sites directly are exposed to hazards like falling debris and bench wall slumping as well as heavy vehicle traffic. Which is where PhotoSat comes in.

In collaboration with Suncor, PhotoSat has developed a process to automatically map toes and crests to an accuracy of 15cm without survey teams requiring access to hazardous areas of the mine site. Production isn’t interrupted, surveyors are working on tasks that actually require boots on the ground, and accurate mapping of toes and crests allows the engineers to monitor bench integrity and check mine progression against projections.

Toes and crests over a satellite photo

Toes and crests data draped over a satellite photo

 

Toes and crests over PhotoSat’s elevation image

Toes and crests data draped over PhotoSat’s elevation image

 

Bird’s eye view of toes and crests over a mine site

Bird’s eye view of toes and crests data over a mine site

 

Mine planning often takes place on a biweekly or monthly basis, reflecting production speed. We’re able to supply our oil sands clients with useable data within 5 days, meaning analysis of progress and erosion is more granular and data is available in a timely manner.

There are several mine surveying options on the market, many of which Suncor has tried (see our first post for Suncor’s comparison of various surveying methods). Typically these rely on LiDAR, which uses reflected laser light to build images. Terrestrial laser scanning involves survey teams setting up and using multiple scanning stations and consequently requires more time to produce images. And survey teams are still on the ground! Aerial LiDAR avoids this issue but results in huge point clouds that have to be processed before an image is usable, which can take a very long time. GPS survey equipment can also be used, but data paucity and safety remain serious issues.

Using satellites, Photosat offers instantaneous snapshots of all mine site toes and crests derived from our elevation grids. Our proprietary geophysical processing system results in far greater accuracy than conventional satellite mapping processes such as photogrammetry.

Oil sands mines change fast and digital vector data for toes and crests are vital to the engineers for keeping track of what is usually softer rock. Suncor switched over to using PhotoSat’s satellite topography as their main survey method in 2013. While some areas of the mine still use GPS surveying, toe and crest mapping has been carried out exclusively by PhotoSat.

Our elevation mapping is also used for other applications at oil sands and hard rock mines, such as:

  • Sloughing in nonactive areas
  • Pipelines and roads
  • Power poles
  • Buildings and structures
  • In-pit geotech surveying
  • Correcting LiDAR issues

For more information on satellite elevation mapping and toes and crests, feel free to contact us at info@photosat.ca or 604-681-9770.

Case study: Reducing Suncor’s mature fine tailings inventory

This post is part 2 in a series looking at how Suncor uses our topographic survey data to  assist their Tailings Reduction Operation (TRO). In this post we’ll look at how they use the data to measure the thickness of their mature fine tailings (MFT) dewatering cells.

Background on mature fine tailings

Mature fine tailings are the clays from the bitumen ore that are suspended in the tailings water. To reduce the area and volume of oil sands tailings ponds, tailings water with suspended clay is mixed with a flocculent which causes the clay to settle out. The tailings water is pumped into dewatering cells where clear water drains off for reuse in bitumen processing while the clay is left behind.

PhotoSat has developed a process to measure the thickness of the clay in each of the mature fine tailings cells in thickness intervals of 15cm. We use our highly accurate topographic mapping between two satellite photo dates to create the detailed elevation maps.

Suncor’s MFT designated drying areas:

  • Total surface area 7.5M m2 (1,866 acres)
  • 697 tailings cells
  • 2788 discharge locations
Suncor mature fine tailings areas

Suncor mature fine tailings areas

 

Zoom of MFT designated drying areas

Zoom of MFT designated drying areas

 

How it works

In last week’s post, we saw that Suncor compared our satellite topographic surveys to other survey methods, and has switched to using PhotoSat mapping as their main surveying method for their TRO operation. The success of this service led PhotoSat, in collaboration with Suncor, to develop a process for automatically mapping the thickness of the mature fine tailings dewatering cells in increments of 15cm. This helps them reduce existing mature fine tailings inventory. The isopachs are provided in map (polygons) and tabular forms.

Satellite photo of MFT system 1

Satellite photo of MFT system 1, July 27, 2014                     Elevation image of MFT system 1, July 27, 2014

 

 

Isopachs (thickness) of MFT System 1

Isopachs (thickness) of MFT System 1, June 29 to July 13                  Thickness changes, July 13 to July 27

 

The spreadsheet data we provide also includes MFT volumes since the last pour, the total area in m2 covered by MFTs, the area of the polygons, the utilization of the polygons, and the MFT lift thickness.

Mature fine tailings mapping from our 15cm accuracy topographic surveys improves the monitoring and measurement of the tailings, providing Suncor with a cost-effective and reliable alternative to GPS surveying and aerial LiDAR mapping. Using satellites also reduces safety risks for field crews.

Next time we’ll look at how Suncor has adopted toes and crests mapping as part of their TRO process.

For more info on our topographic surveys contact us at info@photosat.ca.

 

 

A comparison of survey methods for Suncor’s oil sands mine

At the Trimble Dimensions conference in 2014 Suncor and PhotoSat presented the results of Suncor’s use of our satellite surveying for their Tailings Reduction Operation (TRO) at their oil sands mine in Northern Alberta. The mapping area is about 271 km2.

The full conference presentation PDF can be seen here.

suncor tailings areas

Suncor’s tailings: 50cm WorldView satellite photo                                         1m elevation image

 

In 2012, Suncor’s survey department was given the challenge to do monthly topographic surveys of all TRO cells. They tried surveying with GPS equipment, however less than 20% of the area was safely accessible by ground crews. Suncor also tried 3D scanners but found them very slow, requiring multiple set-ups and the data was sparse. They had previously tried airborne LiDAR but found the point clouds to be prohibitively large, and the data delivery to be frustratingly slow.

In 2013, the engineers at Suncor knew they were in need of a surveying method that would have high accuracy, fast delivery, and improve safety for field crews. PhotoSat stepped in to produce engineering quality elevation mapping from satellite photos quickly and safely. Stereo satellite photos were collected over the mine site, providing a snapshot of the entire site every two weeks. Highly accurate elevation data was then produced from the stereo photos using our unique geophysical processing technology.

We provided Suncor’s team with the satellite survey data within 5 days of the satellite photo acquisition to use at their biweekly planning meetings.

Elevation image differences

Elevation image: January 20                                                           Elevation image: February 23

Many features visible in the January 20 topography were buried by tailings by February 23.

Oil sands sand dump with contours

50cm tailings lift thickness contours: Jan 20 to Feb 23

 

During the presentation, Suncor also discussed the advantages of the customization available with our data. For example, PhotoSat provides Suncor with data in their local mine grid coordinate system. Also, we provided a ‘thinned’ version of the elevation grid, which reduces the density of point clouds in flat areas without degrading the quality and accuracy.

Taking all this into account, since 2013 Suncor has switched to satellite surveying as their main surveying method for their TRO Operation. We have been surveying this area about every 2 weeks since 2013, and continue to at the time of this post.

 

Suncor still uses GPS equipment for surveys of some areas of the mine, but for all the non accessible areas PhotoSat’s satellite mapping is the preferred method. The high resolution elevation data is also used for the tailings pond beaches, as well as mine pit advance and overburden dumps. One of the great features is that the satellite surveying is used by a variety of groups, including Tailings Engineers, Geotechs, and Production Planning.

For the full story, view or download the conference presentation PDF here.

In later posts we’ll look at how Suncor has adopted satellite surveying for mapping mature fine tailings cells, as well as mine site toes and crests.

If you have any questions feel free to contact us at 604-681-9770 or info@photosat.ca.

Penasquito satellite photo

Seeing in Stereo: Satellite Mapping, Mining Volumetrics, and Gold

Peñasquito gold mine is Mexico’s largest gold producer. Two pits, Peñasco and Chile Colorado, produce gold, silver, lead and zinc, to the tune of 567,800 ounces of gold in 2014. The mine sees its future in a copper-gold ore located in tactites beneath the current workings.

Peñasquito’s owners boast proudly on their website that the mine ‘achieved commercial production in 2010, on schedule and on budget.’ That’s no small feat in an industry dogged by unexpected setbacks, and in turn it’s no small measure thanks to fast, accurate and effective mapping and volumetric measurements.

Back in early 2010, Photosat stepped in to calculate mining volumetrics at the Peñasquito mine site.

The goal was to estimate the volume of rock and overburden mined at the site. We used our own high accuracy geophysical processing technology to make volume estimations directly from stereo satellite images that could show detailed 3-dimensional changes.

We started by taking two sets of stereo satellite images, a month apart: one in January and the next at the end of February.

Then we ran these stereo Worldview-2 satellite photos through our own proprietary geophysical elevation processing system.

The beauty of this approach was that we could work directly from the automatically derived elevations to estimate mining volumetric changes in the leach pad, the waste dumps, the ore stockpiles and even the pit itself. All calculations can be done with instantaneous sets of satellite photos – a snapshot of the entire mine site.

Penasquito mine volume decreases

Using the changes in the month-long gap we could determine the volume decrease from January to February, giving highly accurate calculations of the amount of rock and overburden removed from the mine pit.

We based our volume calculations on a 125% expansion factor for blasted rock, and came up with an estimate for the total removed from the pit in a month of 6,928,100 m3 of blasted rock, or 5,542,400 m3 of unblasted rock. This is necessarily a slightly inaccurate figure, but as mining operations go on fine-tuning becomes possible; knowing the proportion of the total removed made up of overburden with a lower expansion factor would tighten up the figures, for instance.

 

Penasquito mine volume increases

Meanwhile, waste dumps, ore stockpiles and leach pads grew by an estimated 6,091,000 m3 during the same period.

 

Leach pad satellite images

This final image shows a detailed view of the volumetric calculations over the leach pad, with an addition of 505,400 m3 over the month.

Find out more about PhotoSat’s mining volume calculations.