A dilettante's comparison of the blenders that can be invoked from PTGui and from Stitcher 5.5 Unlimited:

(PTGui), Enblend and Smartblend

Subject:

What is the effect of the blender S/W when an object moves from one shot to the next in a near synchronous motion as the rotation between each shot?

The blending application takes over in the last step in the sequence to produce a flat panorama. In our study, the 20 original fisheye images of thr sequence (HFOV 140 degrees and VFOV > 194 degrees) were assembled in PTGui 6.0.

The three available blending tools presently available (PTGui stitcher, Enblend and Smartblend) have been successively used.

The blender is provided with an adequate set of images that have been

The idea is to finally simulate the spherical environment that was seen from the camera point of shooting.

But before that step, the blender has to calculate a transition line between the images.
The different blenders use adequate algorithms to find these borderlines. These algorithms are not the same between the three and therefore one can expect to have different results from the same set of input source images.

Moving object:

If an object is entirely present on both adjacent images to be stitched but if it has moved in position from one to the next then the stitcher shall have to resolve this conflicting situation. It does his own way and this can lead to very different outpout panorama images in the end.

It is more a recreational exercise than a scientific research but I enjoyed doing it and wanted to share it with other interested panographers.

Test:

An object was displaced in a synchronized fashion from one frame to the next. The camera was rotated between two shots in such a way that a wheel stayed at the center of the photograph.

Each image looks like this one:

20 images complete a revolution.(Nikkor 10.5 mm adapted to my Canon EOS 5D)

Incidental side product:

After large cropping, dimensions reduction and transformation from fisheye into rectilinear by PTGui application, these twenty images were assembled to make a QTVR Object movie that is posted in the WWP Web site.

Another version of this panorama-object movie was done with Pano2QTVR in flash (BTW, it was my very first experience with this technology)

PTGui 6.0

We have used the same project script that stitched the set of source images exactly the same way except the final blending.

Adding for reference a stitched panorama without blending, four QTVR movies were produced:

Input source image order:

It is easy to change the order of the images in the list (Source images tab window). We have reversed the order to show the impact of such a move:

Stitcher 5.5 Unlimited

This program is fitted with an internal blending function. It's a variant of Smartblend and an option called "Smart" is offered to render the flat sphérical panorama.

Anyhow two external blending modules (Enblend et Smarblend) can also be invoqued after proper selection (only Smartblend seems to be available on the Mac though).

For the sake of completeness, a "linear" rendering as been done even if it is not really appropriate here.

Stitcher 5.5 was not yet able to accept a change in the order for the source images at the time of writting this article (1).

(1) Stitcher 5.5.1 is now able and we are preparing a supplement on this aspect.

Using a single project but by changing the rendering option for blending we got three QTVR movie (~1.2MB)

Illustrated and animated SYNTHESIS (QTVR objet!)

QTVR Objet (600 kB)

Suite (still to be translated from french)

Un autre test a aussi été réalisé dont les résultats sont semblables mais complémentaires à ceux ci-dessus. Des conclusions en sont aussi tirées.

Michel Thoby

Révisé le 1er décembre 2006