image3d in misc3d
Hi, I'm trying to make sense of the image3d plots in misc3d. Unfortunately I can't find any authors on the help pages of the function to e-mail directly. In the following toy example, I'm puzzled as to why (1) the positions of the image plot on the axes include negative values when I think I've specified all to be 1:3 and (2) the logic that needs to be adhered to in order to reliably match up the sphere plot with the image plot. library(misc3d) ##Set up array: arr <- array(1:27, dim = rep(3,3)) ## Plot image, with x, y, z positions all set (I thought) to 1:3 image3d(arr, x = 1:3, y = 1:3, z = 1:3, vlim = quantile(arr, c(0.01, 0.99))) ## Add spheres of the same data at the same positions spheres3d(x=expand.grid(x = 1:3, y = 1:3, z = 1:3), radius = 0.1 *sqrt(arr)) ## Ooops! So why don't they match up? Add axes: axes3d() ## For some reason the image3d is generating negative values of z... spheres3d(x=expand.grid(x = 1:3, y = 1:3, z = -(1:3)), radius = 0.1 * arr^(1/3)) ## But is this reliable? I've tried with a variety of plots and sometimes it seems as though another axis is the negative one... I'm using: R version 2.8.1 (2008-12-22) i386-pc-mingw32 locale: LC_COLLATE=English_United Kingdom.1252;LC_CTYPE=English_United Kingdom.1252;LC_MONETARY=English_United Kingdom.1252;LC_NUMERIC=C;LC_TIME=English_United Kingdom.1252 attached base packages: [1] stats graphics grDevices datasets tcltk utils methods base other attached packages: [1] rgl_0.83-3 misc3d_0.6-1 debug_1.1.0 mvbutils_1.1.1 svSocket_0.9-5 svIO_0.9-5 R2HTML_1.58 svMisc_0.9-5 svIDE_0.9-5 loaded via a namespace (and not attached): [1] tools_2.8.1 Thanks! Colin
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