High Precision Grid Problems

[Luca H]

Hello everybody,

before I start to decribe my problem I want to say thanks, that it is possible at all to work with such precision, it does really make a difference to the quality of the work I produce and it's exactly the reason why I switched to working with the Affinity Apps!

 

Now here's the problem:

I am currently working with a high-precision document where the decimal places for unit types are set to level 6. In this document I have created a rectangular grid, which is also finely calculated with 6 decimal places.

If I now want to align objects to this grid, I run into a problem with the rendering of the grid. The objects do not snap in the middle of the grid line, but somewhere on the side of the line. However, this becomes visible only at an extreme magnification.

The problem is, if I place objects with the size of a grid unit directly underneath each other, at some point they will no longer lie on the grid, because this minimal shift causes the objects to protrude further and further beyond the grid lines.

On top of that some other questions arise. When I zoom to the maximum magnification everywitng I created turns white but what I believe to be the actual grid line (I did not create any guide lines) becomes visible in blue (however this is only true for the vertical grid line). Yet it is not possible to align objecty perfectly with this grid line either. And as you can see the grid lines don't have the same width.This is not really an issue if the objects snap correctly but it looks like it could be related to this problem.

In used Metal as a render engine. I also tried OpenGL, but the problem was not solved.

I attached some screenshots (sorry for the ugly colored text) and a demo file so you can recreate the problem.

 

So that leaves me with the question, is there anything I can do?

If not it would be very important for me to have this problem fixed, since my work depends on this.

Thanks in advance.

Luca

 

 

My setup:

macOS 11.0.1
MacBook Pro (15 Inch, 2019)
Processor: 2,6 GHz 6-Core Intel Core i7
RAM: 16 GB 2400 MHz DDR4
Grafics: Radeon Pro 555X 4 GB
Affinity Publisher 1.8.6 (also checked on 1.9.0.857)

 

 

 

Demo File.afpub

[Old Bruce]

Other than the rendering or the appearance of the Grid (at ridiculously high magnification) are there any problems with snapping to the grid?

[Luca H]

16 hours ago, Old Bruce said:

are there any problems with snapping to the grid?

For this I did a test:

1. I created a rectangle.

2. In the transform panel I set the size of the rectangle to exaclty the size that one grid unit should have.

3. I snapped the object to the grid at a magnification of 300%. It seems to have snapped perfectly.

4. I zoom to 10.000% and I can already see that it's not placed perfectly on the grid line. Zooming even further makes the problem more visible.

5. Now since I work with a grid and I know my numbers and the sizes of everything I can compare in the transform panel if my object is placed correctly, even if it doesn't appear to be.

So one object (as well as a grid unit) has the dimensions of 22,000000 pt x 13,596748 pt. I snapped the object in the 4th grid unit from left and the 4th grid unit from the top. That means the X cordninate of the object should be 22pt x 4 = 88pt and the Y coordinate should be 13,596748 x 4 = 54,386992pt. The attached screenshot shows that it snapped perfectly on the X axis, but on the Y axis it snapped at 54,386904 pt which means that there is a difference of 0,000086 pt.

So to conclude the snapping did not work correctly. 

Also Interesting to see is that when the Y axis is set to the correct calculation (54,386992pt) the object still doesn't correctly sit on the grid.

 

[Old Bruce]

The precision of decimal representation in a binary system is going to create problems like this. One Tenth in decimal is  0.1 in binary it is  0.0001100110011001101 and that is actually a little over .1 (0.1000003814697265625)

The difference of a few millionths of a point over an 8 inch wide document is not going to matter. This is Not A Problem (unless you are doing math for engineers building a bridge).

[Luca H]

9 minutes ago, Old Bruce said:

unless you are doing math for engineers building a bridge

 We're actually trying to do something in this level of precision. 😅

[Old Bruce]

8 minutes ago, Luca H said:

 We're actually trying to do something in this level of precision. 😅

The on-screen / visual representation of the grid should not be a primary concern. Clausewitz said "A map is not the terrain"

I guess what I am asking is does the snapping to grid actually work for your use case versus what does the grid look like at ten thousand percent magnification. Are your little blocks in the proper places is what you should be concerned with, not the look of a drawing aid.

[Luca H]

My current workflow is to use the grid only as a rough estimate where the object should be placed and then enter / calculate the correct position in the transform panel.

 

23 hours ago, Luca H said:

For this I did a test:

The test showed that snapping is not 100% accurate. On the y-axis the snapped object was 0,000086 pt off in comparison to the mathematically placed object. So snapping is not an option. On top comes the inacurate rendering of the grid. Both grid rendering and snapping are not 100% accurate so I stopped using the snap to grid and only use the grid as a guide to see where an object would be roughly placed.

[Gabe]

Hi both,

We are aware of this and it has already been logged with our developers. Snapping(not to grid) should still work correctly. As in, if your object is positioned correctly, and you snap a second object to it(not to the grid) it should have the correct values.