New to laspy and encountering an error. The first code block describes the file header, the second (In[24]) fails to open the file with laspy:
In [21]:
import numpy
import laspy
from laspy.file import File
In [22]:
import struct
headerstruct = ( ('filesig', 4,'c',4) ,
. . . omitted for brevity, see result for fields . . .
('zmin' , 8,'d',1) )
def parseHeader(filename, verbose=True):
# courtesy Phil Wilkes
fh = open(filename,'rb')
header = {'infile':filename}
with open(filename, 'rb') as fh:
for i in headerstruct:
if i[2] == 'c':
value = fh.read(i[1])
elif i[3] > 1:
value = struct.unpack( '=' + str(i[3]) + i[2] , fh.read(i[1]) )
else:
value = struct.unpack( '=' + i[2] , fh.read(i[1]) )[0]
if verbose:
print i[0] + '\t', i[2] + '\t', value
header[i[0]] = value
In [23]:
filename = r'./sf_shared/40095_Flightline_002_Z.las'
parseHeader(filename, verbose=True)
filesig c LASF filesourceid H 0 reserved H 0 guid1 L 0 guid2 H 0 guid3 H 0 guid4 B (0, 0, 0, 0, 0, 0, 0, 0) vermajor B 1 verminor B 2 sysid c gensoftware c TerraScan fileday H 349 fileyear H 2011 headersize H 227 offset L 229 numvlrecords L 0 pointformat B 1 pointreclen H 28 numptrecords L 8917629 numptbyreturn L (6711217, 2002830, 196359, 7135, 88) xscale d 0.01 yscale d 0.01 zscale d 0.01 xoffset d -0.0 yoffset d -0.0 zoffset d -0.0 xmax d 606205.36 xmin d 605000.63 ymax d 6599629.15 ymin d 6596922.71 zmax d 129.27 zmin d 43.74
In [24]:
infile = File(filename, mode='r') #laspy.file.File
--------------------------------------------------------------------------- LaspyException Traceback (most recent call last) <ipython-input-24-19025bf517df> in <module>() ----> 1 infile = File(filename, mode='r') /usr/local/lib/python2.7/dist-packages/laspy/file.pyc in __init__(self, filename, header, vlrs, mode, in_srs, out_srs, evlrs) 60 self.out_srs = out_srs 61 ---> 62 self.open() 63 64 def open(self): /usr/local/lib/python2.7/dist-packages/laspy/file.pyc in open(self) 71 ## Make sure we have a header 72 if self._header == None: ---> 73 self._reader = base.Reader(self.filename,mode= self._mode) 74 self._header = self._reader.get_header() 75 else: /usr/local/lib/python2.7/dist-packages/laspy/base.pyc in __init__(self, filename, mode, header, vlrs, evlrs) 151 self.padded = False 152 if self.mode in ("r", "rw"): --> 153 self.setup_read_write(vlrs, evlrs) 154 return 155 /usr/local/lib/python2.7/dist-packages/laspy/base.pyc in setup_read_write(self, vlrs, evlrs) 162 def setup_read_write(self, vlrs, evlrs): 163 self.data_provider.open("r+b") --> 164 self.data_provider.map() 165 self.header_format = Format("h" + self.grab_file_version()) 166 self.get_header(self.grab_file_version()) /usr/local/lib/python2.7/dist-packages/laspy/base.pyc in map(self) 93 raise LaspyException("Invalid Mode: " + str(self.mode)) 94 except(Exception): ---> 95 raise LaspyException("Error mapping file.") 96 97 def remap(self,flush = True, point_map = False): LaspyException: Error mapping file.
Unfortunately, the laspy documentation leaves you at "When a file is opened in read mode, laspy first reads the header, processes any VLR and EVLR records, and then maps the point records with numpy. If no errors are produced when calling the File constructor, you’re ready to read data!" But it doesn't suggest what to do if there are errors!
Can you see an error in my code or suggest the source of the problem?
except(Exception). Assuming that this code is (or can be) in a stand-alone script, can you run it with the python debugger enabled to halt execution when that exception gets thrown? Something likepython -m pdb myscript.pyshould work. When you're in the debugger you can inspect variables by printing them:p self.fileref. I'd start by seeing if the fileref is closed,p self.fileref.closed, and what the filename is,p self.filename. I don't know what the issue is but that's a way to do a bit of debugging yourself. – Pete Gadomski Feb 7 '15 at 0:16