Make sure you have the latest versions of TerraScan and TerraPhoto installed: P:\Faculty\Chris\LiDAR software\Terrasolid\Terrasolid_Applications (tscan_009.012 and tphoto_009.010 as of September 2, 09)
Check TPhoto settings – automatic tie points off, Coordinate transformation UTM available, Image cache size, laser points Order:before elements
Create file directory as shown
Figure 1.1: Photo Processing Recommended Folder Structure
Images folder should contain the images from Developed folder (JD) that will be used
you may not know which ones you want to use at this stage, so Option A is to put all images in this folder now, and then delete the ones you determine you don't need; Option B is to keep this folder empty until Step 11 (Compute Image List) and then copy in only the final images you are going to work with.
Mission folder should contain the following: template photo .dgn file (new_dgn.dgn); log file and all bak files; desired .cal file (can be created if starting from scratch),
image timing txt file
Trajectory folder should contain: sbet file(s) from Agrgsvr2\Lidar\REALM\IMU\AGRG\2008_256\Proc folder
OR prepared trajectory files
Read in laser points (TScan) – load your prepared Model Key Points file
define area of interest, (use pre-defined dgn with blocks for Waterville or Middleton for calibration, outline the survey area with a polygon, or refer to a previously set up project for the survey)
IF you need to prepare trajectories – in TScan:
Set directory
Import sbet file
Draw into design – Level = Trajectory
Delete outside polygon – create bounding poly, select and delete
Draw new lines into design file – delete unneeded ones
Renumber trajectories and delete the sbet – large file not needed anymore
Define new Mission in TerraPhoto - SAVE immediate after creating
Set directory paths
Set up camera file by clicking
Add… - select the .cal file from the most recent calibration for lens type (RGB or NIR)
Figure 1.2: Define Mission and Mission Camera dialogue boxes
Set directory in TPhoto for trajectories (no thinning) – Manage camera trajectories
Load points from Tscan (mkp las file already loaded)
Compute image list; add text file created – SAVE – Tphoto is calculating position and orientation for each frame using the time stamp to link them to the trajectory information. Each frame is scaled using the MKP’s TIN, so each pixel has a correct xyz value.
(Create Thumbnails and/or tile images if larger than 100
MB) - optional
View foot prints – delete unneeded photos – ie. Poor overlap – Utility: Draw Footprints
Review Camera view of images – make sure photos and laser data match reasonable (in same projection, geoid adjustment)
(Define colour corrections) – this is where you would do it in Terra – but better to look at this when mosaicking in PCI
Define Tie points – three working windows
Work through several manual iterations until mismatch is low (SAVE iterations of tie points file)
Collect ground points
‘Recompute all’
‘Output report ‘ – see Figure 1.3
Enter Heading, Roll & Pitch values to camera file, click ‘Apply’
Re-run output report to ensure Start and Final average values don’t change
Figure 1.3: Tie point report
Change to semi-automatic tie points collection (in settings (see Figure 1.4) – check box ‘Find matches automatically), when mismatch distances are relatively small (less than 10 pixels on the ground) (in example, one pixel = 5 cm, so less than 50cm mismatch), and you have a relatively good distribution of points on a few images.
Figure 1.4: TerraPhoto settings dialogue
Fully automatic search - When mismatch values are small (7cm in demo) start to search for points automatically.
Min contrast between 30 and 100
Match limit between 6 and 12 (6= tightest)
Distance limit (max allowed mismatch distance for a pixel to be accepted)
With auto-search you can identify a class containing high veg, building tops for generation of Shadow Maps’ areas – these areas will not be searched, reducing raster mass of images, and decreasing processing time and the need to delete bad points.
Always filter and delete bad points after automatic search
Iteratively – ‘Find Worst’ & ‘Delete’ or
‘Filter bad’ – 3.0 times average and less
Processing time: added 116 points, 40 minutes over 10 images
Continue until satisfactory average is reached; small numbers, little change – 20+ fully defined images and your misalignment angles should not change significantly unless other camera parameters are changed.
Adding points and deleting worst pixels: target distance limit is 5x the pixel size or less. Ruggles 10cm pixels, so 50cm or less.
When using Filter Bad – start with 3 times average ratio, then move down in increments after re-computing and applying new parameters.
Check individual image deviations for particular images that may be worse than others. Go that image and delete worst pixels.
When the modifications of the tie points list no longer has any significant effect (level of changes is 0.0001 or so), choose Solve parameters under Tools menu.
Solve for all parameters
Click ‘Apply’
Re-compute all using new camera calibration values
Output report – adjust RPH values in calibration file
Click ‘Apply’ again.
This should hold for surveys –
only need to do on calibration flight data
Figure 1.5: Solve camera parameters dialogue
When numbers are small and you are satisfied – Adjust positions – Heading, Roll and Pitch angles (only do this once, SAVE output report) – adjusts the position and rotation of each image using a file or active tie point list.
SAVE the adjusted image list and adjustment report (note the tie points file is no different in content; image list contains rph changed values) note: you don’t see the difference unless you open files in a text editor
(Create colour points file and SAVE to mission folder – to be used in Mosaic function) - optional
Rectify images - OPTIONAL (writes out images to ‘rectified’ folder – tif, tfw, jpg2000 or ECW)
Create tile rectangles - Place Array
Naming is automatic with this – check text style if you want to be able to read it
MAKE SURE NAME STARTS WITH A LETTER
Pay attention to the final size of each rectangle – memory problems processing – 450m x 450m too large
To create an Orthophoto mosaic in TPhoto
select tiles & names to be ortho mosaic’d
choose ‘Rectify Mosaic ‘to create orthophoto mosaic (longer to process than rectify images)
1.84 km2 took 5 minutes to process – from RAW, no tie points
1.84 km2 took 6.5 minutes to process – from RAW, tie point refined, using color pts
1.84 km2 took 21 minutes to process – from ADJUSTED, tie point refined, using color pts
Figure 1.7: Quick Ortho Mosaic Settings
To display orthos – open Manage Raster References and ‘Attach files’ or ‘Attach directory’ (can also select this option in ‘Rectify’ dialogue box
Figure 1.8: Ortho - based on RAW positions
Figure 1.9: Ortho - based on ADJUSTED positions - in-depth workflow
