using imagestation automatic triangulation (isat)
Contents
1. USING IMAGESTATION HEXAGON AUTOMATIC RECREATE TRIANGULATION ISAT eTRAINING Introduction Performs automatic measurement of tie and pass points in the photogrammetric project Software e ImageStation Data e Aalen Dataset Transcript 0 09 0 34 0 44 Thank you for watching this Hexagon Geospatial eTraining module Using ImageStation Automatic Triangulation This eTraining module will walk you though the steps needed to perform Automatic Triangulation including automatic point matching Before performing the automatic point matching you will e Create a block of photos e Measure the control points for the block and e Define the ZlJobService login After performing the automatic point matching you will e Merge the measurements back to the main project e Compute a final bundle adjustment and e Analyze the results This workflow begins with ImageStation open a project created and the camera information defined The first step is to create a block ISAT processes photos in groups that are referred to as blocks Large projects are often broken into smaller overlapping blocks for project management purposes This is a very small project so you ll create a single block that contains all photos 1 Navigate to ISAT gt Block Preparation 2 Type any name for the Block ID such as all_photos 3 Click Add All to add all photos to the block and then click OK to create the block and to close the dialog2. Using ImageStation Automatic Triangulation ISAT Point Measurement 1 24 2 26 Next you ll use the Point Measurement command to measure the project s control points in the Multiphoto Orientations environment While it is not mandatory that control points be measured before running the matching process it s good practice so that you can determine if your input GPS IMU or other exterior orientation or EO approximations have been entered properly 4 Navigate to ISAT gt Point Measurement 5 Select all photos from the Available Project Photos list to add them to the Selected Session Photos list 6 Select any two photos from the Selected Session Photos list to add them to the Selected Display Photos list and click OK 7 Open the Advanced dialog select All Points in Project and uncheck User Manual Points and click OK 8 Select the first control point in the list then click Go To 9 Click Yes Always when prompted to save changes This causes all photos that the control point projects to to be displayed at the control point s projected location 10 In one of the Detail views center the cursor over the target and click to record the measurement ISAT will automatically transfer the measurement to the other photos If a point fails to transfer automatically simply center the cursor over the target in the Detail view of the measurement that failed and record the measurement manually 11 Repeat this process
3. e photos Blunder detection algorithms are also used to eliminate erroneous measurements and control points 6 50 7 05 7 45 8 08 8 32 Using ImageStation Automatic Triangulation ISAT There are three ways to run the bundle adjustment in ISAT e Use Orientations gt Photo Triangulation gt Triangulation e Use ISAT gt Point Measurement gt More e Use Orientations gt Multiphoto gt More The second two methods are exactly the same and have the advantage of allowing you to drive to points for re measurement when you find any that are suspect The first method runs the same adjustment program but runs outside the point measurement environment You ll use the third option 32 Click Orientations gt Mutliphoto 33 Uncheck the Adjust Displayed Photos Only option and click OK 34 From the Multiphoto Orientation dialog click More and click Options 35 Under Adjustment Modes select Absolute 36 In the Adjustment Options select check Enable Precision Computation and Enable Compute On Edit 37 In the Given EO GPS INS Settings section check Enable Given EO 38 In the GPS Correction Setting check GPS Correction 39 From the Vertical drop down select Linear Shift Drift Per Strip 40 Under INS Correction Settings check INS Correction and then click OK 41 Click Compute to run the bundle adjustment 42 Navigate through the tabs to check the adjustment results 43 On the Point Statistics tab sort th
4. e points by the V xy column and find the worst point 44 Click on it and then click Go To Point 45 Click in any of the Detail views to remeasure the point or use the Withhold or Delete buttons to eliminate the point 46 Click Compute to re run the bundle adjustment and check the results 47 When you are satisfied with the results click Apply or OK to save the results Using ImageStation Automatic Triangulation ISAT Densify the Control Points List 8 51 9 31 9 55 This optional step is to write the adjusted tie pass points object coordinates into the Control file 48 To do this navigate to Orientations gt Photo Triangulation gt Densify and click OK to update the Control point list 49 When you open the Footprint Viewer you can see that all the Tie Pass points have been converted to Control points 50 You can also view them by using Edit gt Control Points This project is now ready for e Orthophoto production using ImageStation OrthoPro ISOP e DTM extraction using ImageStation Automatic Elevations ISAE or ISAE Extended or e Stereo feature collection using ImageStation Stereo Display ISSD or ImageStation Stereo for GeoMedia ISSG Thank you for watching this eTraining module from Hexagon Geospatial For more eTraining visit hexagongeospatial com eTraining
5. for the rest of the control points in the list 12 When you have finished measuring all six points click Apply and then Close 13 Use the Footprint Viewer to verify that all control points have been measured 14 Click Tools gt Footprint Viewer Configure ZlJobService 3 18 If the images for your project are on a remote server or system you need to change the Log On settings for ZlJobService 15 To do this click the Windows Start menu button and navigate to Computer gt Manage The Computer Management dialog opens 16 Click Services and Applications and click Services Scroll down and click ZlJobService The ZlJobService properties dialog opens 17 Click the Log On tab and change the log on account and password to a valid domain and username that has Read access to the remote system 18 After making the changes select and right click ZlJobService and click Restart Using ImageStation Automatic Triangulation ISAT Automatic Tie Points 4 17 4 49 Next use the ISAT Control Panel to execute and monitor the automatic tie point matching process 19 20 Zi 22 23 24 Click ISAT gt Control Panel For this project under Post Processing check Stringent Matching and click Thinning and Weak Areas to open the dialog Under Thinning Options select Thin using 9x9 grid and check Remove Single Rays in Strips and Remove 2 Ray Points in Triple or More Overlap Areas Under Weak Area Options selec
6. t Analyze using 3x3 grid Click Accept Click Submit to begin the processing A project of this size should finish in about 10 minutes After the job goes from the Queued state to Running you can use View Log File to monitor the process Verify and Merge the Results 5 16 5 46 When a block is submitted for matching ISAT creates a sub project in the project folder with the same name as the Block ID 25 26 27 28 29 30 31 To verify the results of the matching navigate to ISAT gt Set Active Project and select the sub project Use the Footprint Viewer to check the Tie Pass Point distribution In the Footprint Viewer dialog check Tie Pass and uncheck Labels When a project has any weak areas you would use ISAT gt Edit Weak Areas to pick the points and let ISAT drive you to them so that you could add measurements to the weak areas To edit weak areas click ISAT gt Edit Weak Areas Use ISAT gt Set Active Project to return to the master project Use ISAT gt Merge Block Measurements to copy the results from the sub project up to the master project For large projects that are broken into sub blocks you would use this command to merge them all back to the master project for a final bundle adjustment Final Bundle Adjustment 6 32 ISAT uses a bundle adjustment program that is referred to as PhotoT to compute adjusted object coordinates for the tie pass points and adjusted EO parameters for th
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