"I have a structure"
No, you have not. As your screenshot shows (and just pasting the code would have been better, see Stephen's comment), you have an object of class lasdata.
The syntax for accessing object properties and structure fields might be the same, but they are very different things. In particular, the lastdata class is obviously a handle class, hence all copies share the same memory.
If plotLevelLiDARdata was a structure you would have seen this:
>>plotLevelLiDARdata
plotLevelLiDARdata =
struct with fields:
Unless the lasdata class has its own copy method, or it derives from matlab.mixin.Copyable, the only way for you to create a copy is:
data = lasdata;
data.x = plotLevelLiDARdata.x;
data.y = plotLevelLiDARdata.y;
data.z = plotLevelLiDARdata.z;
edit, now that you've posted the details of the lasdata class:
The above won't work because lasdata constructor needs at least one argument. More importantly, the author of that class did not appear to be fully familiar with access protection but it's clear that he did not intend for the user to be able to change the properties of the class.
If you really need several distinct instances of the objects, you need to create them all from scratch, with no copy:
filepath = fullfile(inFilepath, '000415_elli_85_0002.las');
originalData = lasdata(filepath);
dataCopy1 = lasdata(filepath);
dataCopy2 = lasdata(filepath);
If the copies of the object don't need to be instances of the class (i.e. you don't intend to use any of the lasdata methods on them), you could also do:
originalData = lasdata(fullfile(inFilepath, '000415_elli_85_0002.las'));
dataCopy1 = struct(originalData);
dataCopy2 = dataCopy1;
