Rendering quality less good than in 0.6

[aurelienb]

In the same kind of trouble, the link render is not very well (at least at default value)
And it sometimes provoke curious viz' (the horizontal link near the mouse is half cut, because it is not totally horizontal)

Pictures with bad link render

(I think there is also a trouble with arrow on short link but I cannot redo at this moment)

[mbastian]

Thanks for feedback. There are some explanations for differences between 0.7 and 0.6 edges rendering. The technique is not the same. Now 0.7 engine can display edges thickness, and therefore draw edges in a different way, which is not as much antialiased as drawing lines in 0.6.In the 0.6 version, with ou without antialiasing, edges were looking fine.

I'll check on my side if there isn't a bug about antialiasing and if edges can be rendered more smooth. With proper antialising, it is as nice as 0.6 on my computer.

@aurelien On your screenshot you don't have any antialiasing

[jacomyma]

Maybe it would be good to:
- switch the default antialiasing to 8x
- put a default "edge zoom" (the slider) to a more "thick" value, because thicker edges have less artifacts

[jacomyma]

Thinking about that...
It looks that there is now some convergence about what we expect from nodes, edges, and labels as graphical objects:
- "screen size" or "zoom size"
- Color and size set by a parameter (ranking, partition)
- Show / hide (all or by filtering)
- Tweak global size (the sliders)

For the moment the labels are the most settable graphical objects, but this discussion leads to generalizing these options and maybe build a more unified, more consistent UI for these...
For example, nodes are always "zoom sized" but it's an interesting option to have them "screen sized", some graph softwares already work like this. The same way, edges may look nicer if "screen sized" like in 0.6 and this option isn't useless for simple unweighted directed graphs. And I notice that it doesn't prevent from sizing by a parameter, and it is easy to set a "good" size with the sliders.

So the panel in the bottom of the graph may have four sections: node, node labels, edges, edge labels
And each section may have these options: "show / hide", "screen size/zoom size", "appearance", "global size slider"
Of course appearance would be different for each type (edges="source node, target node, chosen color", node labels="node color, chosen color; font" ...)

Finally this also asks the question of "proportional node labels" versus "make it proportional manually by ranking"

[seinecle]

Just to add:

Anti-aliasing is not supported by my laptop graphic card, which is very standard I think:

- Mobile Intel(R) 4 Series Express Chipset Family (installed on an ACER Aspire, 2009 model)

And anti-aliasing is supported up to 6x by the graphic card of my desk computer, which is a very standard graphic card as well I suppose:

- ATI Radeon X1300 (installed on a DELL, 2006 Model).
(so for both graphic cards, aliasing is still very much present at 4x, 8x or 16x for Gephi 0.7).

So as a user, I suppose that the rendering quality should not depend on anti-aliasing, and just function as Gephi 0.6 did.

[aurelienb]

My laptop is old so I am used to desactivating AA. I do not remember but, if I can apply AA only for edge I can try but if AA concern edge and nodes (as usual Viz engine) I probably cannot use AA on standart graph I use.

[mbastian]

Gephi render engine is built for performance and therefore rely on anti-aliasing for edges quality. But that shouldn't be a problem, as you have the "Preview" module to create nice anti-aliased maps. From this module you export your map as SVG and then the anti-aliasing is not a problem, as SVG is a vectorial graphic file.

@aurelienb: AA is a general setting, that apply on 3D polygons (nodes and edges).

You can usually force AA setting in your graphic card driver panel, or let application decide.

[seinecle]

Hi,

It really depends on how you use Gephi. This Tuesday I will make a presentation showing networks, and how they spatialize. What when you erase a node, what when you move one, what when you change the gravity parameters... all this not in the preview mode. So I need a perfect rendering quality. Also, with the dynamic arriving, what if the movies of networks evolving can't be seen in the preview mode? So they would also need a perfect rendering since the start.

If anti-aliasing, even at x8, is not supported by most graphic cards, I think it is good to reconsider its use by Gephi. Mathieu, just try to use Gephi 0.7 for a week on a computer without anti-aliasing capabilities, and tell us then if you don't reconsider your approach!

I decided that I had to use Gephi 0.6 instead of Gephi 0.7 for my presentation, and in my view this tells it all.

[seinecle]

To qualify a bit what I just said: maybe that I am a bit too ignorant of these questions.

Thriving for performance is certainly good, especially since progress in hardware will allow soon, if not now, to handle commonly what Gephi offers. I just really don't know how many users would have *today* computers that are compatible with the features, like 16x AA, which come with this increased performance.

A simple way to measure this would be: can anybody tell me the starting price for a laptop equipped with a graphic card that would support 16x AA?

Thx,

Clement

[mbastian]

According to your screenshots, I'm pretty sure you don't have anti-aliasing at all. Check your graphic drivers and configuration.

It really depends on how you use Gephi. This Tuesday I will make a presentation showing networks, and how they spatialize. What when you erase a node, what when you move one, what when you change the gravity parameters... all this not in the preview mode. So I need a perfect rendering quality. Also, with the dynamic arriving, what if the movies of networks evolving can't be seen in the preview mode? So they would also need a perfect rendering since the start.

Yes that is true, I understand the quality problem. But we can't do anything about it...Gephi use OpenGL for displaying graphs...and OpenGL rely on your hardware. Most of users have compatible graphic card that has anti-aliasing capabilities. I tested it on a Notebook, with anti-aliasing and it was looking great.

Note that color and edge weight is changing a lot how edges are aliased.