Reading 3DM file using OpenNURBS - expected output file size


When reading a 3DM file using OpenNURBS and exporting the contents to a human readable text file, what is the expected size of the text file?

For example, suppose that the 3DM file is 14MB. Should the output text file via OpenNURBS be similar in size or a fraction of the size? When I used OpenNURBS on a sample 14MB 3DM file, the exported text file was just 80KB.

I’m curious as to whether writing the text file (80KB) back to 3DM using OpenNURBS will generate the exact same 3DM file in the same size (14MB). Any insights would be appreciated. Thank you.

Hi @Richard_James,

I doubt it’s possible to answer this question.

How are you outputting the text file? OpenNURBS does not save in a text file format, btw.

– Dale

You could be missing for instance embedded image texture files, preview thumbnails, render meshes, etc.

Hello Dale, thanks for the response. Is there a feature in OpenNURBS that allows it to read the 3DM file and then output all the contents into text that is readable by humans?

Hi @Richard_James,

No. As I said above, openNURBS does not save in a text file format.

Why do you need this?


– Dale

Hi Dale, I would like to have the ability to manually view & edit the contents of the 3DM file in plain text without using Rhino or any other software. My understanding is that OpenNURBS can read from and write to 3DM files and must store the contents somewhere. Surely, there must be some way to view the contents and then save it to a text file?

Hi @Richard_James,

The openNURBS toolkit is the library Rhino uses to read and write .3dm files. The .3dm file format is binary.

Perhaps you can use Rhino to save files to some 3rd party text format - .dxf perhaps.

Not sure how else to help, sorry.

– Dale


I was informed by someone that I can use the “ON_Object::Dump” method to get the text description of each object. Will this method dump all details of each and every object into text such that the text would describe the model in its entirety?

Hi @Richard_Jamesm

ON_Object::Dump does ouptput a text description of objects that inherit from ON_Object.

Rhino’s List command uses this.

But the text dump is incomplete and only for debugging purposes.

– Dale