Soon there will be many hearts.
Here is a first attempt to convert it to a Symmetrical Lattice.
Soft Pillow or Balloon Heart?
I have been trying that out today and got some nasty artifacts how did you get this so smooth? I made a hieght map, saved it as an 8 bit grayscale .bmp at 2048x2048 res and I didn’t get a smooth result.
Nicely done btw.
I am no expert at this but i will tell you what i did.
First i made a Bryce Heart Model. Then i set it up for a distance render down the Y-axis [could use height render also]. I used heavy DOF to blur the edges. I rendered at a very high resolution  to get the Grey-scale map. Export as TIFF 24 bit. Then in Terrain Editor at  load the TIFF.
The manipulations are complicated and intuitive. If i mess up i simply try again.
First we drop the resolution from 2048 to 512 or even 256.
Make sure the contrast gradient from white to black is not maxed out [usually it is not as the render will be quite flat and not display all the values from white to black].
Invert image and smooth very heavily then invert again and reduce the contrast gradient otherwise we get a flat spot in the middle.
Alternate this smoothing with application of Gaussian edges.
Toward the end bump up the resolution one step at a time and apply smoothing at each step making sure a flat spot does not develop in the center. Till we get to 1024 or even 2048. But usually 1024 is enough.
As i said i mess up all the time and i try again and again.
Finally bring up the clipping bracket.
This sort of processing does loose some of the outline of the shape. It becomes more rounded. If you don’t want that then this method is not suitable. For Balloon Hearts it is of course ideal.
Like playing a musical instrument you need to play with this and practice.
I could write a step by step procedure of the process but that would take many weeks and i am sick of doing tutorials.
You could also start with only an Object Mask Render [or if you are not a Bryce purist with your ideal heart shape created in Photoshop]. Then you would create all the volume only with Gaussian Edges.
There are millions of ways to do this but the objective is to get a very smooth surface in the end without loosing the shape.
Hope this helps a bit.
Remember you can always reload the basic Grey-scale shape and try again.