[ome-devel] Plans for Shoola Hierarchy Visualization client

[Harry Hochheiser]

Andrea, Jean-Marie, and I had a very productive discussion this morning 
regarding implementation plans for the Shoola hierarchy viewer.  This 
note is my attempt at summarizing our discussion and plans....

Currently, there are two related shoola clients that can be used to 
browse/view various pieces of an OME hierarchy. The data manager 
provides a standard, tree-based view projects, datasets, and images.  
This uses a standard GUI expandable-tree widget to display 
relationships in a strict hierarchy. This provides a familiar 
interface, at the expense of potentially obscuring non-hierarchical 
relationships. For example, a dataset that appears in many projects 
will be listed multiple times, making it potentially difficult to 
answer questions such as "which projects is this dataset in?"

The zoomable browser presents a list of projects along with a gridded 
overview of available datasets. Linkages between these items convey 
information about the many-to-many mappings: mousing over a dataset 
leads to highlghting of the names of the projects that contain the 
dataset, etc. Each dataset display contains thumbnails in a grid: users 
can zoom in to see individual thumbnails as needed. Both of these views 
link to the Shoola image viewer.

The zoomable browser has some known problems: the thumbnails presented 
are not multi-scale, so they can become grainy at high magnifications. 
There are also some disorientation problems that arise upon zooming out 
to a high-level view.

A more fundamental problem with the zoomable browser involves a 
mismatch with user needs. Users will often be interested in a specific 
dataset. When this is the case, they should not have to navigate 
through a display containing numerous images from other datasets.

Both browsers are currently limited to addressing only the 
project/dataset/image hierarchy. Although obviously an important part 
of OME, this is not the only image hierarchy that  is possible.  
CategoryGroup/Category/Image and Screen/Well/Plate/Image are other 
potentially desirable groupings, each with its own specific 
constraints.

As I understand it, Jean-Marie and Andrea are going to build an 
abstract model for representing these possible hierarchies. This model 
will be accessed from the data manager, with code from the zoomable 
browser providing the basis for an image browser:   selection of a pair 
of projects in the data manager will lead to a zoomable browser window 
containing both projects, each of which would be divided into datasets 
as appropriate. Zooming into datasets would be supported as before. A 
project or  dataset could be selected by clicking on its title: this 
selection would cause the zoomable browser to devote all available 
space to the dataset/project and its contents.

Selection of a category group (perhaps through the data manager?) will 
cause the currennt display  to be divided into subgroups based on the 
classifications within that group. (this raises questions: if I have 
multiple datasets on the screen, should I I re-arrange images based on 
dataset first, and then category within dataset, or on category first 
and then dataset.)

In the short term, I will also try to fix the main known bugs in the 
zoomable browser: the disorientation on zoomout and the lack of 
multi-scale thumbnails.

Once the basic integration of the data manager and the zoomable browser 
is in place,  there are several interesting opportunities for 
enhancements that might provide significant value to users. 
Possibilities include:

	- Linked views: alternative views of a given image set might be 
dispayed in adjacent windows, with coordination between the windows 
demonstrating correspondence. For example,  a window showing images 
divided into n categories in a group might be adjacent to a display of 
those images in m datasets.

       - Improved methods for selecting hierarchies and internal nodes 
for examination: the data manager is not ideal: is there any way that 
the functionality for browsing projects, etc. might be integrated into 
the window that displays the image views?

	- Drag and drop modification of hierarchies: recategorizing images by 
dragging them from one category's area to another.

    - Support for customization of thumbnail rendering, perhaps on a 
per-hierarchy basis.


    - Visualization of large datasets  - potentially holding >=10K 
images. This would probably be done via an overview window that would 
show the location of a detail view in a larger image grid.

My understanding is that Jean-Marie and Andrea have committed to 
getting some of the basic functionality complete by April 15.  After 
that, we will discuss and prioritize these other goals.

-harry