ImageMagick Convert: How to produce sharp resized PNG files from SVG files?
I had the same problem, but I sort of went around it by setting the density first.
From command line:
for %f in (*.svg) do (convert -antialias -background transparent -density 600 -resize 1024x1024 %f %~nf.png)
convert -density 2304 pinterest.svg pinterest.png
Because the original DPI is 72 and the pixel size is 16x16, so 512/16*72 is 2304.