reading .xyz file format

Programming Questions

dvnanness

in Programming Questions • 2 years ago

I am trying to read the CAD format .xyz which:

Header:

4 bytes: XYZ1

2 bytes, unsigned int: Width

2 bytes, unsigned int: Height

Data:

ZLib-compressed. Use ZLib.dll uncompress to decompress it...

The output size of the data is (image and palette):

(Width * Height) + (256 * 3)

The input size of the data is:

FileSize - 8

In english, the data starts after the header and ends at the end of the file, and the image, when decompressed, is just a palette and then image data.

The palette is simply a series of colors in RGB order, no 4th byte for the palette entries.

The data is just a bunch of palette indexes, in standard x,y order.

and looks like:

Comment lines begin with '#" in column 1, and may appear anywhere;
Blank lines may appear anywhere.
The coordinates of a point are written on a single line, separated by spaces;

Example XYZ File:

 # Corners of a tetrahedron # 0.0 0.0 0.0 1.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 1.0

what are the suggestions on reading this into processing?

There is one C++ library that will read this format, but obviously it isn't processing.

I am wondering if I could read it as a string and then split it back up as needed.

Replies(3)

PhiLho

Re: reading .xyz file format

2 years ago

Looks like you describe two different file formats, one binary holding an image (indexed colors, similar to Gif), another textual holding coordinates.
Have you references, samples files?

dvnanness

Re: Re: reading .xyz file format

2 years ago

http://people.sc.fsu.edu/~jburkardt/data/xyz/xyz.html

PhiLho

OK, looks like being purely textual, no bytes nor zlib-compression, at least as described in the page you point to.
Just read the file using loadStrings, and iterate on the strings, rejecting the blank ones and those starting with a #.
On data lines, you just use split() on space to get an array of strings, which you convert to float using float().
That's all.

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