nanoDLP

I guess (Shahin will know better) because what you are going to project to resin is an array of pixels (your projector resolution). So generating PNGs with the exact resolution of your projector should ensure projector pixels will match the slice image pixels. This enables to exploit at maximum your theoretical resolution.
If image resolution is readapted at the projection time, you will never know if pixel correspondence would be correct.

Not sure if all I am going to say applies to LCD technology, as all I have read is about DLP, but in theory should.
With DLP you just have an array of pixels (micromirrors) , so projected matrix of pixels should match in theory.
What can be happening is that your pixels have diamond-orientation (45º inclination relative to the matrix frame). I think this is more common on general purpose screen/projectors, as they can give a visual perception of better resolution.
In this case the projector usually remaps the input image to your screen (Great simple explaination in this video). This give the kind of aliasing you are seeing.
Some projector have a "pattern mode", so you can directly control each pixel value even if diamond-oriented. Anyway I am not sure changing input image could solve the problem.Not at a physical level at least, you will always have a remapping of your HDMI video output to the real screen matrix.

PS: I take the chance to ask, in case Shahin will answer the post: does NanoDLP make use of grayscale to obtain sub-pixel resolution? Would it be possible to add this option to the slicer or use an external slicer and upload it as a plate? I mean something like this.

Rob,
As Steve mentioned it is same as AA. Or atleast result should be very close.
Any vector (SVG/STL etc) graphics will get converted to raster format before could be displayed on GPU.

However the way raster get converted to raster format could affect image/print quality.

Rob, yes there are always grey pixels on a sliced png from NanoDLP. Here is the top slice from the 3dSLA_Test, the model that is giving me this angst. The top is with anti-aliasing on, bottom off. The dots are vertical cylinders, but still, there are solid pixels and grey pixels. Even in the walls of this model, there are halftones in the AA version, which result in my model looking a little soft, out of focus.

Shahlin, my point with svg is that these would be perfect circles, perfectly straight lines. Then, it would be up to the LCD's GPU to decide the best way to pixelate those circles. "Best in, best out."
Currently, NanoDLP decides first, then the LCD does it again. "Rubbish in, rubbish out."

Here is the same top slice, but at double the resolution. "Better rubbish in, better rubbish out."

I've not yet been able to print my theory of doubling the screen resolution in NanoDLP's set up page, along with a similar 'cheat' in the profile's 'R D Override X/Y Resolution.' I think my troubling dots/tiny cylinders would come out better, they look better in the above slice, this surely would allay my woes. Though I'm sure there will be a gotcha somewhere, otherwise, you would have designed NanoDLP to do it this way: 'better rubbish in, better rubbish out.'

Again, I understand that the LCD's GPU cannot understand the depth of the model, cannot add anti-aliasing in the right places - that's the slicers job. But, at very, tiny, tiny layer heights anti-aliasing loses its wonders.

Wha? Oh no! You're saying my 'correct sized' 2k, 1440 x 2560pixel 5.5" screen, a pixel density of 534.038 ppi slice -  the one that currently is made by NanoDLP - gets mashed through the Raspberry Pi GPU, and then is re-mashed through the LCD's GPU?

'Rubbish in, rubbish mashed, worse rubbish out.' Three levels of pixelisation. Hell's bells, no wonder I'm having trouble getting those tiny cylinders to print. Humph! I thought there would be a gotcha somewhere. Thanks, Rob ;-)

But surely, HDMI can take 4k, why would it crush my double sized slice? Wouldn't that be up to the end user - the LCD's GPU? Is there no hope? Can I not lie to the Pi's GPU, tell it to send 4k, and let the LCD's GPU to sort it out? Sigh, I'm out of my depth here, telling lies to a computer is not my area of expertise. Honest Steve, they call me. ;-)

Last edited by Stevehoo (2017-11-24 12:22:04)

Thank you, Rob. Though bearer of the bad news - that I cannot lie and cheat to get 4k through to my 2k screen, you've been a great help.

pi@nanodlp:~ $ tvservice -s
state 0x120006 [DVI DMT (87) RGB full unknown AR], 1440x2560 @ 50.00Hz, progressive

All is well with my RPi, at least, it thinks so.