2 Session Overview Company Background Principals of Photogrammetry 3DM Analyst Mine Mapping SuiteComponentsGeneral WorkflowKey FeaturesImage Capturing MethodsApplicationsCommon ProblemsQ&A
3 Company Background20 years’ experience in the photogrammetric industry (founded in 1986)Designed, manufactured, and sold hundreds of analytical stereoplotters worldwide, including many MPS-2s to mining companiesEmbarked on what was to become the 3DM technology (3-dimensional, Dynamic Measurement) in 1996Developed and installed many custom photogrammetric factory control systems in Japan for glass bottle making (3DM Gob) and rubbish pit control (3DM Bunker)Wholly Australian-owned private company — all research, development, and manufacturing conducted in Perth, Western Australia
4 Principals of Photogrammetry The location of any point in an image canbe described with just two co-ordinates:(x,y). Images are only two-dimensional.The location of any point in the real worldcan be described by three co-ordinates:(x,y,z), (latitude, longitude, altitude), etc.The real world is three-dimensional.Photogrammetry is the science of using 2D images to make accurate measurements in 3D. To do that, the information that was lost when the image was captured needs to be recovered.
5 Principals of Photogrammetry Problem: The light that hits a given pixel in the image could have come from any point along the ray from the pixel, through the perspective centre, into the scene.Possible points of originTop-down viewImageSensorFocalLengthPerspective Centre
6 Principals of Photogrammetry Solution: Adding another image taken from a different location allows us to intersect the rays and determine the 3D location of the point where the light came from!Top-down viewImageSensorUnique 3D location!
7 Principals of Photogrammetry Information needed to determine 3D locations:The location of each camera’s perspective centre.The orientation (rotation) of each camera about its perspective centre.The location of the point on each image sensor.This is the essence of photogrammetry!Exterior OrientationImage Matching
8 Determining Exterior Orientations Absolute orientation:All data is registered in a real-world co-ordinate system using known points (control points and/or camera stations)At least three known points required in project (regardless of how many images are used)Relative orientation:Data is registered in an arbitrary co-ordinate system (can be specified)Scale normally provided by known separation(s) between camera positions and/or known distances between points in sceneAll images in project must be “connected”
9 Determining Exterior Orientations Inputs:Image co-ordinates of all control points and relative-only pointsImage co-ordinate sigmas (Sx,Sy)Control point co-ordinatesCamera station co-ordinatesIndividual co-ordinate sigmas for both control points and camera stations (Sx,Sy,Sz)Outputs:Adjusted image co-ordinates for all pointsAdjusted control point co-ordinatesExterior orientationsDerived ground co-ordinates for all of the relative-only points
10 Important Characteristics of Photogrammetry Relatively range-invariant — simply choose the lens required to obtain the desired ground pixel size:ImageFocalLengthImageFocalLengthObject
11 Important Characteristics of Photogrammetry Accuracy highly configurable — planimetric accuracy depends on image accuracy and ground pixel size; depth accuracy additionally depends on camera separation:Good values for :0.5: Conservative value for planning0.3: Reasonable estimator of actual accuracy in most cases0.05: Best value actually observed (circular targets)
12 Visualising AccuracyThe relationship between accuracy in the image, planimetric accuracy, depth accuracy, and base:distance ratio can be visualised by looking at the “error ellipse” that is formed when we adjust the location of the point in each image by the image accuracy:Error Ellipse
13 Visualising AccuracyIncreasing the base relative to the distance makes the error ellipse more circular, improving the depth accuracy:Error Ellipse
14 Measured Accuracy BHPB Iron Ore, Mt Newman: Application: Geotechnical analysisTypical working range: 700m to 1.2kmNominal ground pixel size: 4cm × 4cmTypical accuracy: 0.1m to 0.2m
16 Measured Accuracy Fugro Spatial Solutions, Western Australia: Application: Measuring road subsidence while train tunnel being constructed underneath itWorking range: 20mGround pixel size: 0.5cm × 0.5cmAccuracy: m! (Surveying retro-reflective targets)
17 Measured Accuracy How is it measured? Most comprehensive: Manually measure control points in 3D images, compare with surveyed locationsEasiest: Read bundle adjustment report to see residualsGood practice: Withhold some control points to act as “check points” — residuals should be the same as the control points actually usedCaveat: Need redundancy for this to work! Only three known locations data will fit perfectly and residuals will be 0!Problem: Reported accuracy will never be better than the actual accuracy of the survey data!
18 3DM Analyst Mine Mapping Suite Digital photogrammetric system designed to work with modern digital cameras:Automatically determines relationships between camera positions (relative orientation) simply by inspecting imagesAutomatically generates 3D surface data from imageryPowerful vector data digitising and editing tools with over 160,000 user-defined feature types supportedExtensive operator assistance whenever human input is requiredBuilt-in digital camera calibration routines
19 3DM Analyst Mine Mapping Suite 3DM CalibCamPerforming camera calibrations (interior orientations)Determining exterior orientations (camera positions and directions) for any number of images simultaneouslySurveying targets accurately (up to 80,000:1!)Creating extremely high-resolution merged images3DM AnalystGenerating, editing, and merging DTMsDigitising vector data using Single Image mode, Stereo, or 3D modeAnalysing data — volume calculations, face detection, etc.Exporting data as 3D Images, DXF, etc.DTM GeneratorGenerating DTMs and resulting 3D Images in batch mode
20 Workflow Geotechnical analysis in VULCAN: Capture Images 3DM CalibCam or 3DM AnalystDetermine camera orientations3DM Analyst or DTM GeneratorGenerate DTMs & 3D ImagesImport 3D Images into VULCAN for interpretationVULCAN
21 Workflow Other applications: Capture Images 3DM CalibCam or 3DM AnalystDetermine camera orientations3DM Analyst or DTM GeneratorGenerate DTMsAnalyse data: calculate volumes, digitise vector data, etc.3DM Analyst
22 Key Features Ease of use Accuracy Speed Flexibility Works with any digital cameraWorkflow is extremely automated and robustIntelligent troubleshooting built-inAccuracySpeed15 seconds to automatically determine camera orientations; five minutes to generate 250,000 DTM points on a 2GHz PCFlexibilityWorks with images captured in any environment under almost any circumstancesCan be used for almost any task where accurate 3D data is required
23 Ease of Use DemoThe only thing not automated is determining the location of the data in the physical world!
24 Flexibility — Image Capturing, etc. Images can be captured in any configuration (convergent; strips; fans), even in the same projectNo pre-requisites on camera orientations — software will work that out automatically!Any control data supplied in any configuration and with any accuracy will be used in the solutionCamera calibration can be performed on an ad-hoc basis if required using the same imagery as captured for the project and it can be analysed to ensure validity
25 Image Capturing: Independent Models Optional overlap between modelsPros:Conceptual simplicityFlexibility — depth accuracy can be freely adjusted by changing base, can be used with lenses of any focal length over any distanceCons:Each model needs to be fully controlled (at least three known locations — control points and (optionally) camera stations)Extremely vulnerable to bad control due to low level of redundancy
26 Image Capturing: Image Strips Series of parallel images overlapping neighbours by at least 50%. (May be arranged in multiple rows, overlapping about 10%.)Pros:Gives accurate exterior orientations with very few control points — one control point for every five images is generally more than adequateIdeal for aerial imageryCons:Base is determined by field of view, which is determined by focal length — best with short focal lengths
27 Image Capturing: Image Fans Series of images overlapping neighbours by about 10% captured from each camera stationPros:Fewer unknowns give strong orientations with very few control points — minimum is one control point plus two camera stations for entire project!Very fast — rotating camera to capture next area much quicker than relocating cameraImages can be merged (and treated as independent models in 3DM Analyst) allowing very high resolution images with cheap camerasFirst modelSecond model
28 Applications — Geotechnical Analysis BHPB Diamonds Ekati Koala mine:Camera: Nikon 1Ds, 135mm lensProject area: 500m × 300mNumber of images: 27 from each camera stationNumber of camera stations: 2Distance to pit wall: 700mGround coverage: 120m × 80m per image (3cm pixel size)Number of control points: 7 (placed around the top of the pit in safe locations)Accuracy: Sx = 0.14m, Sy = 0.08m, Sz = 0.04m.Processing time to generate 3D images from scratch: 4 hours, only 8 minutes of which was actual user time!
30 Applications — Geotechnical Analysis Key advantages:Data can be obtained remotely when there is no safe access (up to 3km away!)Features can be identified that would not be apparent at close rangeSpeed of acquiring data compared to other methodsAccuracy and detail of data compared to other methodsAcquiring the data has little impact on other activitiesImages form a permanent record that can be referred back to in the futureThe physical components — the parts that can break down — are relatively cheap, available from many suppliers, and easy to replace
31 Applications — Aerial Mapping Thiess Indonesia:Camera: Canon EOS 300D, 28mm lensProject area: 140km (captured in one day)Number of images: ~1,200Flying height: 600m – 800mGround coverage: 600m × 400m per image (20cm ground pixel size)Accuracy: 0.2m
32 Truck Volume Calculation Other ApplicationsResource ModellingTunnel MappingTruck Volume Calculation
33 Exciting New Developments Cost-effective aerial photography using fully autonomous UAVs:Ideal for pit mapping and stockpile volume calculations2 hour endurance, 100 hour service interval, 6,000 feet ceilingOnboard GPS for autonomous navigation — program in desired camera locations as waypoints, UAV captures images from each waypoint in turn
35 Common Problems Bad imagery: Poor quality images — blurry, badly exposed, optically different from calibration use prime lenses, tripod, aperture priority (f/8), focus at infinity (or use autofocus at distances similar to calibrated distance)Incomplete coverage of area being mapped plan better, capture redundant images (images are cheap!), go back and capture additional images if possibleBad observations:Bad control point/camera station co-ordinates plan for redundancy so bad points can be disabledIncorrect observations of points in the images correct them!Insufficient relative-only points reduce matching tolerance, use a lower ISO setting to reduce noise, digitise one or more “seed” points manually
36 Common Problems Bad DTMs: Large number of bad points increase matching tolerance, use automated spike removal tools, use a lower ISO setting on the camera to reduce noiseIncomplete/sparse DTMs reduce matching tolerance, use a smaller base, use a lower ISO setting on the camera to reduce noise, digitise data manually as a last resort
38 3DM Analyst Lite Designed for customers with less demanding workloads: Can calculate exterior orientations for two images at a timeSupports images of up to 16 megapixelsCan upgrade to any other product in the range at any time simply by paying the difference in list price for the software and support agreementADAM Price Guarantee: List prices for upgrades are fixed as long as your ADAMcare support agreement is continuously maintained
39 3DM Analyst Lite Suite Combines 3DM Analyst Lite and 3DM CalibCam Lite Designed for customers with larger workloads and who want to reduce the number of control points required for absolute orientations:Can calculate exterior orientations for up to 10 images at a timeSupports images of up to 24 megapixelsSupports image merging allowing cheaper cameras to be used to generate high-resolution images
40 3DM Analyst Mine Mapping Suite Combines 3DM Analyst, 3DM CalibCam, and DTM GeneratorDesigned for customers with very large workloads and who want to be able to calibrate their own cameras:Can calculate exterior orientations for any number of images at a timeSupports images of up to 65 megapixels (on a PC with 2GB of RAM)Supports image mergingSupports camera calibrationSupports batch processing of any number of DTMs offline (+ generate 3D Images from them) without human interventionSeparate dongles for 3DM Analyst and 3DM CalibCam so both can be used simultaneously on separate PCs
41 3DM Analyst Professional Designed for professional mapping organisations working with large format scanned images:Can process any number of images at a timeSupports images in excess of 250 megapixelsSupports batch processing of any number of DTMs offline (+ generate 3D Images from them) without human intervention