Exact placement of objects??

[Bradj2]

Please can someone explain why a faint gap exists between 2 objects after positioning them on exact coordinates?

E.g.
X2, 2cm squares are drawn with no line fill and positioned on top of each other (X=6cm & Y=12cm) and (X=6cm and Y=10cm).

Why the faint line between the vertical boxes?
Thanks,
Brad

[steve.ledger]

Depends on the zoom level and the dot (pixel) pitch of your LCD panel.
On LCD monitors, dot pitch is typically from .16 to .29mm.

No gap here at 125% / 200% / 320% / zoom

Tried printing it?

[handrawn]

Screen anti-aliasing is a/the factor here - it bugged me for a while

try dropping your view quality - I use xtreme pro 5, and gaps are visible with high quality and very high quality views - but not at full color view, which has the anti-aliasing turned off, with this settings no gaps at any zoom on my LCD monitor...

[steve.ledger]

Very true Steve (but doesn't text look ugly ) and is why it (the anti aliasing) is concealed it at certain zooms relative to dot pitch.

At the end of the day, two shapes touching might just as well be welded (Add Shapes) unless there is a specific reason why two identically coloured shapes with no gap need to be kept separate?

[handrawn]

sure

its useful sometimes to view things or export them without the anti-alias, and its helpful to understand why it is happening in this case, but not necessarily
good to work at the lower setting

'not seeing the joins' between objects on different layers [so that optional stuff can be switched in and out] is my main run in with this....

[michaelward]

Because Xara's representation of real world measurements may not align with the pixel boundaries of your monitor, Xara will ant-alias the edges of your shapes (use shades to give the effect of sub-pixel drawing).

If you changed your page measurement to pixels, and aligned using pixel measurements then you would not see the effect (at 100% zoom).

If you're doing on-screen graphics, use pixels as your measurement. If the document is intended for printing, then use real world measurement systems (cm, inch, etc.) and accept that the anti-aliasing issue is just an on screen artifact.

[dpt]

This is an anti-aliasing artefact. There's no actual gap inbetween the objects.

Each object is individually rasterised and anti-aliased onto its background. This piecemeal rendering results in the white background showing through. The anti-aliased edges between the two boxes /ought/ to contain 50% of shape A and 50% of shape B, but in practice there will be 25% of whatever background colour contributed to those pixels.

It's interesting to compare this against Flash, which uses a different model. It scan converts in a single pass, so no background colour shows through.

If you change zoom level you'll see the effect vary.

[handrawn]

If you changed your page measurement to pixels, and aligned using pixel measurements then you would not see the effect (at 100% zoom).

interesting - any chance of an example?

This is an anti-aliasing artefact. There's no actual gap inbetween the objects.

yep - see post #3

[Egg Bramhill]

Here you go Steve. You shouldn't see the join at 100% zoom but you do see it at 75% zoom as the resolution forces aliasing.

[handrawn]

thanks Egg - at the end of the day then, there is no way to have high quality view and not experience this at some zoom levels?

pity...