Smart Cropping to get a sharper Panorama

<<How to>>

Part II

Foreword

Smart Cropping possible object and purpose have been shown in another page (click on WHY WOULD YOU SMART-CROP? button from the navigation bar at the top). This is now the "How To" Smart Crop.

The tutorial is based on Canon EOS 20D (2,336 x 3,504 pixels / 15.0 x 22.2mm CMOS Sensor) and Sigma EX 8mm Fisheye lens.

Some experience in using PTGui is needed to get satisfactory results. In any case the step numbering will help but deviation from this workflow is possible.

A simpler but less capable similar way was described in another page (click on WHY WOULD YOU SMART-CROP? button from the navigation bar at the top).

Second method: Crop and Stitch in PTGui (not yet supported by PTMac)

Technical preamble (can possibly be skipped over)

A fundamental feature of PanoramaTools (and that is also adopted in the recent PTGui v5 autonomous engine) is that every image to be stitched can be singularly described in both the Optimizer and Stitcher scripts. These scripts can be read by mark checking the appropriate boxes while this is not mandatory.

All the parameters and coefficients of every "i" line can have a different value from any other "i"line. That is to say: any to-be-warped/stitched/blended image can be different e.g. have been shot with another lens, or with another camera or come from different source(...scanner), etc.

A directly related fact to be known is that the "Lens Type" which is specified in 2 places now (i.e. "Project Assistant Tab" and "Lens Settings Tab" in PTGui 5+) becomes arbitrary and are without effect on a given image as soon as this image is given a independent status (i.e. when "Use individual lens parameters for:" box is check marked for this image). Hence, the word "Lens Type" in the "Images Parameters" table means more accurately "Cropping Type" under these circumstances because it then does specify the Cropping characteristics applied to the image rather than to the lens that was used to shoot this photograph...

The confusion between the real meaning of the "type of lens" in the different Tab pages has thus to be avoided. For example, when the lens type that was used for shooting could have been a "circular fisheye", the "Lens type" in the two said Tab pages could be set (note: they are synchronized by PTGui) as "Fulframe" while the setting in the column "Lens type" of the "Images parameters" table could be "Fulframe" (another image could being set as "Circular" and have also a different "fov" as well). This apparent hodgepodge can be simultaneously set on purpose and actually correct.

"How to Smart Crop" Workflow

Only six photographs are used here: four horizontals plus one Nadir and one Zenith. This is the usual number that I use for high quality "architectural type" panorama on tripod.

Unlike the precedent case (click on "HOW TO, Part i" button from the navigation bar at the top), no crop has been done at all prior opening PTGui 5. The six photos are coming right from conversion from RAW to TIF in PS CS in my personal case. They could be JPEG's directly coming from the camera.

Illustrated Workflow for the Stitch in PTGui (Click on Picts to Enlarge)

On the opening Tab page "Project Assistant" several settings are equally possible:

Fulframe 113,5 degrees, Fulframe 180 degrees, Circular 180 degrees shall in fact produce later on, the same result for reasons given above in the technical preamble.

The later value is selected.

Project assistant Tab The setting value of 179. 01 degrees come from a PTGui project template that carried this value over here.

Standard circular Lens type

Let PTGui find pairs of control points and it also should place all the six image at its place in the Panorama Editor at this stage after activation of the "Generate Control Points" button.

Source Images Tab The Tif images comes from conversion from RAW format.

See enlarged version of te image in the "Control Points tab" section below.

2336 x 3504 pixels

Lens Settings Tab All images have "Individual Parameters Settings" selected.

The shown coefficients are value come from an intermediate optimization run

Note that this page shall have to be accessed in several occasion in the course of the process.

Panorama Settings Tab Standard settings for a Full spherical equirectangular panorama

Crop Settings Tab 1

The Orange grid shall serve as tracer to clearly see what part of this image is visible in the final panorama.

The settings shall command the crop of 2266 x 2266 pixels. This square part should be only taken into account for further processing. Click on "Apply to all images".

Advanced users: Other type of crop could be used (see "Images parameters")

Crop Settings Tab 2

The Red grid shall serve as tracer to clearly see what part of this image is visible in the final panorama.

The crop settings are the same as for the first image.

Advanced users: Other type of crop could be used (see "Images parameters")

Crop Settings Tab 3

The Green grid shall serve as tracer to clearly see what part of this image is visible in the final panorama.

The crop settings are the same as for the first image.

Advanced users: Other type of crop could be used (see "Images parameters")

Crop Settings Tab 4

The Blue grid shall serve as tracer to clearly see what part of this image is visible in the final panorama.

The crop settings are the same as for the first image. processing.

Advanced users: Other type of crop could be used (see "Images parameters")

Crop Settings Tab 5

The Cyan grid shall serve as tracer to clearly see what part of this image is visible in the final panorama.

The crop settings are the same as for the first image.

Advanced users: Other type of crop could be used (see "Images parameters")

Crop Settings Tab 6

The Magenta grid shall serve as tracer to clearly see what part of this image is visible in the final panorama.

The crop settings are the same as for the first image.

Advanced users: Other type of crop could be used (see "Images parameters")

Images parameters Tab The settings come from the final optimization.

As "Individual Parameters Settings" were selected (Images Parameters Tab) Any "Lens type" could be selected, thus commanding the crop type (Crop Tab): "Circular" or "Fullframe" could do as well, one or the other.

Only "b" coefficient was Optimized, "a" and "b" were kept at nought. (see Optimizer tab). The fov is <110 deg as expected.

A bug created some artifacts

The "Lens type" is set to the same for all images. This is simpler to manage but not mandatory.

Control Points Tab The CP were first created by the "Auto Create" new functionality of PTGui 5.

Note the nice spreading of these points and note also the grid color that differentiate the images.

Optimizer Tab All images could have had identical parameters and coefficients.

However, all parameters were here individually specified, but the type of lens.

Preview Tab I rarely use this functionality. These are default settings, I can imagine.

Create Panorama Tab

One of numerous possibilities as the FOV<110 degrees allows using PTGui new internal engines amongst the other older possibilities.

Panorama Editor The six images participate about equally: look at the "colored grid" relative area and location.

Conclusion

The benefit of the cropping is illustrated in a separate page. Click on the "SYNTHESIS / Illustrated Comparison" button on top of the page

Pros:

Cons: