[R] R package for reading / writing 3D file (. PLY)

[kvarpun]

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 at 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 at 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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