systems colliding

belkina · September 27, 2019, 11:42am

This kind of collision happens to me from time to time no matter what number I put in the Inter-system Gap in the setup. Lillie Harris mentioned that it has something to do with Dorico’s calculations going round in circles otherwise. I would suggest that since nobody EVER wants this result, when the algorithm gives this result, it would be best to just start a new frame.

Thanks!

pianoleo · September 27, 2019, 11:46am

Daniel at Steinberg:

The problem here is that Dorico does not know exactly how much vertical space the music is going to occupy until it has cast it off, but it cannot know exactly how to cast it off until it knows the height of the music, so this is an inherently circular problem.

When the 'Automatically resolve collisions between adjacent staves and systems’ option is on, then Dorico makes an estimate of what it thinks the height of the system(s) is likely to be prior to casting it off, so that it can decide when it needs to move on to the next frame; the reason it has to work this way is that the next frame may not be the same size as the current one – in particular, it could be narrower or wider, in which case the casting off might need to change.

So before it casts off it needs to try to work out how many systems it can fit into the current frame at the current width. It can’t do the final layout yet, because some of the things it needs to lay out cannot be laid out until we know how wide the frame is etc., so it’s using a relatively crude estimate based on the kinds of items you have in each system. Low and high notes contribute, as to lyrics, dynamics, tempos, and so on. I hope that one day we’ll be able to come up with a better approach to this inherently rather circular problem, but as yet we haven’t got one!

In your score, Dorico assumes that based on its estimates two systems will fit in the height of the frame, but when it comes to it and the systems are taller than it expected, then you end up with collisions, because it can’t change its mind and force one of the systems into the next frame on its own. However, adding a frame break manually should sort things out.

(„Resolve the collision..” strange behavior - Dorico - Steinberg Forums)

dspreadbury · September 27, 2019, 5:30pm

Couldn’t have said it better myself. Wait a minute…

pianoleo · September 27, 2019, 5:35pm

My thinking was that nobody else could have put it better than you, Daniel, so why bother trying?

belkina · September 27, 2019, 7:02pm

Lol, thanks for the explanation. Yes I do add frame breaks manually, but as you may know, in a large condensed score it is VERY slow. I have a PC with 64G of ram, 6 processors, and it can take about 30 seconds to insert a frame break.

I have to say that at some point in the process, e.g. after Dorico has “concluded” the calculations you describe, Dorico should be able to simply add together the heights of the two systems and check that they don’t overlap on the page. And if they do, insert a frame break. Since this would affect the overall page layout but not the casting off within each system, it seems to me like it should be fairly simple.

Thanks again for your reply.

Have a good weekend,

Alan

dspreadbury · September 28, 2019, 8:52pm

There is little more insidious than a comment from a user along the lines of, “it seems to me like it should be fairly simple”.

Derrek · September 28, 2019, 9:42pm

Isn’t there some saying

“For every serious problem there is a simple, obvious solution.
–And it is inevitably wrong.”