Duncan Murdoch-2 wrote: > > On 11/12/2009 11:37 AM, kvarpun wrote: >> >> Duncan Murdoch-2 wrote: >>> >>> On 11/12/2009 4:56 AM, kvarpun wrote: >>>> Hi, >>>> >>>> Is there an R package that reads and writes 3D images having the >>>> extension >>>> PLY (PLY images of Stanford University)? >>>> >>>> Currently, I installed the package misc3d. This package displays these >>>> images PLY, but it can neither read nor write PLY images. >>> >>> This doesn't make sense. How can it display PLY images if it can't read >>> them? Could you give an example? >>> >>> Duncan Murdoch >>> >>>> >>>> Thank you to tell me the name of a package that will read and write >>>> such >>>> images. >>> >>> ______________________________________________ >>> R-help@r-project.org mailing list >>> https://stat.ethz.ch/mailman/listinfo/r-help >>> PLEASE do read the posting guide >>> http://www.R-project.org/posting-guide.html >>> and provide commented, minimal, self-contained, reproducible code. >>> >>> >> >> Thank you for quick answer. >> I have to inform you that the only available functions in the package >> misc3d >> are: >> >> contour3d Draw an Isosurface, a Three Dimension Contour >> Plot >> drawScene Rendering of Triangular Mesh Surface Data >> image3d Draw Points on a 3D Grid >> kde3d Compute a Three Dimension Kernel Density >> Estimate >> makeTriangles Triangle Mesh Functions >> parametric3d Draw a 3D Parametric Plot >> perspLighting Lighting Functions >> phongLighting Lighting Functions >> pointsTetrahedra Create a Set of Tetrahetra Centered at Data Points >> scaleTriangles Triangle Mesh Functions >> slices3d Interactive Image Slices of 3D or 4D Volume >> Data >> surfaceTriangles Create a Triangle Mesh Representing a Surface >> teapot Utah Teapot >> translateTriangles Triangle Mesh Functions >> updateTriangles Triangle Mesh Functions >> >> None of them does read/write a PLY file. >> >> >> You will find below a simple code for drawing a 3D image. The displayed >> image is stored in the package misc3d (not read from a file). >> >> library(misc3d) >> data(teapot) >> >> haveRGL <- suppressWarnings(require(rgl,quietly=TRUE)) >> ttri <- makeTriangles(teapot$vertices, teapot$edges, color = "red", >> color2 = >> "green") >> >> ## draw the teapot >> drawScene(ttri,screen=list(y=-30,x=40), scale = FALSE) >> >> str(teapot) >> # > str(teapot) >> # List of 2 >> # $ vertices: num [1:3, 1:1976] -3,00 1,65 0,00 -2,99 1,65 ... >> # $ edges : int [1:3, 1:3751] 1455 1469 1459 1449 1455 1459 1462 1449 >> 1459 >> 1469 ... >> >> # My images (PLY images) have vertices and edges like the teapot image in >> the example. If PLY images are read by R, I will be able to manipulate >> them. > > Okay, I understand now. Yes, R can display 3D images based on lines and > polygons using the rgl package or scatterplot3d or grid graphics, but > those have nothing to do with PLY files. As far as I know there is no > existing code to read or write a PLY file, but from the look of it, it's > a simple format and it wouldn't be hard to write input/output routines. > The likely problems are: > > - it's an open ended format, with each application allowed to define > its own record types. If your files come from an application that did > that you may have trouble working out what was intended and reading it in. > > - some of the recommended elements are not supported in rgl or other > 3D renderers in R. In particular, polygons with more than 4 vertices > need to be decomposed into triangles or quads, and rgl knows nothing > about refraction index: you'd probably need a ray-tracing renderer for > that. > > - rgl scenes contain text, and as far as I can see, there's no way to > include that in a standard PLY file, so you'd need to invent your own > record type for it. Text is always hard to describe graphically, so > this wouldn't be easy. > > Duncan Murdoch > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > > Thank you for all these precisions. I guess developping an R package for reading/writing PLY files is required. Have a nice day.
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