Scanned Film Verticals, Cropping Black Borders
Vertical images on film made with large format calibrated cameras were used for photogrammetric mapping since the 1930's or earlier. There are millions of these images in the archives of the mapping services for all countries. Usually, the transparencies or negatives show image data in a black background surrounding the image. If these are not removed by cropping when the images are scanned, that must be done in AirPhotoSE before attempting to stich a sequence together to display a wide area at high resolution.
Load a set of scanned vertical film images for orthophoto production with Select.
Click on the Crop Verticals button. The first image in the selected sequence will be shown with a cropping frame.
Drag this so that none of the surrounding black border and it's content is visible within the frame.
You can move from one image to the next or back by clicking on the Next or Previous buttons to view the images singly. Make sure that the cropping frame does not include any of the black borders in any of the images. If it does, reduce its area by dragging on the side white dots. Test the output by clicking on Crop.
If you are satisfied with the result, click the All Images button and then on Crop again. All the images you have selected will be cropped automatically and written to new files with the word "Vcrop" before the period to the left of the file extension.
Close the cropping window with the Close button.
The cropped images will be shown as thumbnails.
With the Options button in the Orthophoto main dialogue window, choose Defaults, but uncheck UseGUI and then click on Run in the main Orthophoto window. Bundle adjustment will run normally. Click on Apply, and when "Job Done" is shown, click on OK and select Container in the dialogue displayed. The Container is a blank black window large enough to display all the partial orthophotos in their proper places. Click on View to display the rough initial results.
The partial orthophotos created by Bundle Adjustment and Cloud Compare will be shown. Usually, there will be very visible seams and differences in exposure and colour if colour images were loaded. You can also examine the result from stitching with Microsoft ICE by clicking on the ICE menu item. The seams will usually be gone, but contrast and visibility of fine features of interest may not be visible. ICE chooses it's algorithm for geometry automatically unless the manual entry options on it's file menu are used. One of the three Planar Motion options is required to display image geometry correctly. If there are problems, ICE may choose to display "Rotating Motion" which maps the images to a cylinder. It is possible to choose Planar Motion after ICE has made one try, but if there are placement problems, Rotating Motion will then be used again. This can be overridden by entering all the partial ortho-image names manually using ICE's File menu option of "New Structured Panorama".
Close the Quick View window.
Click on the Options and choose one of the Enhancement features, then Run again and View and ICE as before until you are satisfied with the result. Then open Options yet again and select "High Resolution" and reduce the size of the Sample window to 800 or less to reduce computing time, close Options and use the Run, Apply and View sequence again to obtain the final result. Usually AutoContrast or Luminance will be sufficient, but in difficult cases Auto Colour Enhancement (ACE) or in extreme cases, Retinex may be used at the expense of colour distortion in the result.
You can zoom into the result stitched image and examine detail in the context of the large scale image which the programme has made.
If your machine is running with a 32 bit operating system, the 32 bit version of Microsoft ICE may run out of memory with a number of large original images. The Container option does not have this problem, but the result quality is usually lower, because there is no blending or adjustment of minor positional errors. One solution is that if you have access to a machine with a 64 bit version of Windows, then AirPhotoSE will automatically use the 64 bit Version Of ICE if you have installed it. A better solution is to configure your machine to boot both the 32 and 64 bit version of your operating system if your hardware supports this.