plot3d smooth lines problem

Hi,

I created a scatterplot using the plot(3D) package in R. The code is as follows:

scatter3D(x = avg_f1, y = avg_f2, z = avg_f3, xlab = "F1", ylab = "F2", zlab = "F3", col = group_col, pch = 16, type = "h", axes = TRUE, label = TRUE, nticks = 5, ticktype = "detailed", box = TRUE, bty = "g", colkey = FALSE, cex.lab = 1, cex.axis = 0.7, cex = 2, lwd = 2, colvar = NULL, phi =20)

text3D(x = avg_f1 , y = avg_f2, z = avg_f3 , xlab = "F1", ylab = "F2", zlab = "Duration", col = group_col, pch = 16, type = "h", axes = TRUE, label = TRUE, nticks = 5, ticktype = "detailed", box = TRUE, bty = "g", colkey = FALSE, cex.lab = 1, cex.axis = 0.7, lwd = 2, labels = averages$vowel, add = TRUE, colvar = NULL, cex = 1.5, phi = 20)

Picture1
As you can see, the plot appears fine, but I want to make the droplines look smooth.

Any ideas?