The "best size" varies , depending on the intended output . Right now I'm working on an animation project that has a final output of 2K (2048 x 1536) but it is being animated at 4K (4096 x 3072) , which allows for the final images retaining a very sharp line quality after they are down-scaled from 4K to 2K .
Keep in mind that all images generated in TVPaint are at 72 dpi (as are all computer images) . As has been mentioned numerous times on this forum, DPI only has reference to printing images , it has nothing to do with animation. For illustrations intended for printing , you should scale up the pixel dimensions to match the intended size you will print it . Here's how it is stated in the TVPaint FAQ
DPI only matters when you're printing things out. DPI is used to indicate how dense the image resolution will be when you will print your illustration. The resolution is measured in Dots-Per-Inch, and the higher the DPI rating, the finer the detail the printer will attempt to print.
In animation, DPI resolution is usually irrelevant since you don't print animation. Worrying about DPI in an animation is like worrying about FPS (Frame per second) in an illustration.
Nevertheless, you can convert illustrations made in TVPaint Animation with most desktop publishing programs. You can also simply increase your project's resolution to match the required DPI.
A 8x10" project printed @ 72 DPI = 576 x 792 pixels
A 8x10" project printed @ 300 DPI = 2400 x 3300 pixels.
So in this case if you wanted to print your illustration to 8" x 10" , in TVPaint you should set the project pixel dimensions to 2400 x 3300 .
This pixel calculator tool can help you find the ideal size for illustration projects intended for printing: https://www.pixelcalculator.com/
For television broadcast 1920 x 1080 (16:9/1.77:1 aspect ratio) is a fairly standard size for final output , but as Animark mentioned above, it's common to work over-scale . I would tend to usually work at 1.5x - to - 2x the intended output . So for 1920 x 1080 I might set my project size for 3840 x 2160 (which is 2x 1920 x 1080) . The Camera View would be set to 1920 x 1080 , so when the project is exported it will be at 1920 x 1080 , but because I'm working over-scale I can move around within that larger space and zoom-in slightly without degrading the line quality. However, if I have a scene that is planned to have a very long zoom-in range where the camera starts from a very wide view and then moves in to a very close view then I would set the project size for that shot at much higher dimensions, maybe 4x larger , so that would be 7680 x 4320 . That size would allow for a zoom-in range that is equivalent to a zoom-in from '12 Field' to '3 Field' in traditional animation . (referencing the traditional "12 Field graticule/field guide"
) , keeping the image sharp throughout the zoom range. It's pretty rare that you would need to zoom-in that tight (equivalent of '12 F' to '3F' ).
The formula to keep in mind is that the final field of the zoom-in must equal the intended output size
, so when it ends up at "3 Field" (the tightest fielding) the size must be 1920 x 1080 . Does that make sense ?
For a zoom-in that doesn't go in as tight , the original project size doesn't have to be as large. If the zoom-in range was equivalent of '12 Field' to '6 Field' then your original project size would only need to be 2x over-scale at 3840 x 2160.
As long as you're not going any tighter than '6 Field' you can move the camera around within that space in a 3840 x 2160 project . However , for shots where the camera is locked off , then just work at the intended output size (1920 x 1080 or whatever your final output is going to be) . Even then I might tend to work at around 120% over-scale (2304 x 1296) as a rule , so in case I need to shift the artwork or re-field slightly tighter I have that leeway .
See the attached movies. The first one shows a zoom-in that goes from 7680 x 4320 (400% over scale) to 1920 x 1080 (100%) . The final movie was exported to Camera View of 1920 x 1080. Notice that in the first movie the image stays sharp for the entire range of the zoom-in.
The second movie shows the same zoom-in , but the original project size is 1920 x 1080 zooming-in over the same range. Notice how by the time the camera gets to the tightest field the image has become blurry.
That's the nature of working with pixels . You have to compensate for how much those pixels are going to be enlarged. In both cases the final output was the same: 1920 x 1080 , but in the first version because the original project size was 4x over-scale (7680 x 4320 ) and the camera ended up at 1920 x 1080 , the image stayed sharp .
For theatrical exhibition 2K has been standard (although 4K is on the ascendancy , and some advocating for 8K , although for theater showings it is questionable whether anything is really gained by going over 4K . In many ways 4K or over is detrimental for drawn animation, because it shows flaws that are not visible at 2K . But that's a whole other topic ... )
For 16:9/1.77:1 aspect ratio at 2K the output size would be 2048 x 1152 . For 1.85:1 theatrical aspect ratio it would be similar : 2048 x 1107.
For the animated feature film 'Song of the Sea' (made with TVPaint) the files I've seen show that for scenes with a locked-off camera they worked at a size of 2304 x 1296 , with the actual Camera parameters set to 2048 x 1152
(16:9/1.77:1) . I think the extra size of 2304 x 1296 was simply to allow for some border area around the main image , to allow for minor adjustments to the compositions . For scenes with camera movement that involved zooming-in closer they would have worked at correspondingly higher dimensions in the original file size , although the camera parameters would have been at 2048 x 1152 , so the final scenes are all output to 2048 x 1152 at 16:9/1.77:1 aspect ratio. I saw this film in a theater on a very large screen and it looked gorgeous. Actually, it's very interesting to note that a film like 'Song of the Sea' doesn't have a lot of complicated camera movement. The camera is more often locked off for most scenes and something interesting happens within the scene
, that is to say, the animation creates the interest , not the camera movement . Some filmmakers lack confidence and are constantly keeping their camera in motion (and for certain types of action sequences this is appropriate) but camera movement (especially inherently artificial movement like zoom-ins or zoom-outs) is too easily over-used in place of having something interesting happen in the animation . But again, that's another topic ...
I hope this gives you some clarity on the size to use for your projects.