Files & Layers

This section provides details about creating and modifying .pix files (Geomatica’s working file format). Recipes in this section also demonstrate how to import foreign file formats into .pix and conversely, exporting .pix files to foreign file formats.

The PCIDSK (.pix) file format is a very powerful, flexible and clean file format. As a database file, it can store hundreds of raster channels of varying bit-depths, vector segments, bitmaps and many other layer types in a single file. Unlike, flat files where projection, attribute information, metadata and imagery/vectors are all stored in separate files, the pix file holds everything in one, easy to use file.

Create .pix (PCIDSK) file with empty channels defined

This recipe demonstrates how to create a projected .pix file with empty image channels defined. Imagery can then be directly copied into these empty channels.

from pci.cimpro2 import cimpro2

new_file = r"C:\FilesLayer\empty_file.pix"
create_channels = [4,0,1,2] #creates 4 8bit, 0 16bit signed, 1 16bit unsigned and 2 32bit real channels
data_layout = "PIXEL" #creates data structure for file as 512x512 pixel tiles
projection = "UTM"
zone = [55]
row = "G"
datum = "D000" #D000 is WGS84. Also note that D122 is NAD83
top_left_x = "514418.000"
top_left_y = "5262616.000"
bottom_right_x = "527908.000"
bottom_right_y = "5246564.000"
res_x = "2.0"
res_y = "2.0"

cimpro2(new_file, "", create_channels, data_layout, projection, zone, row, datum,
        "N", top_left_x, top_left_y, bottom_right_x, bottom_right_y, res_x, res_y,
        "", "", "", "", "", "", "", "", "", "", "", "", "", "", [], [])

Create .pix (PCIDSK) file with no projection defined

This recipe creates a .pix file with empty channels defined by pixels and lines, but a coordinate system is not defined

from pci.cim import cim

new_file = r"c:\new_file\empty_file.pix"
file_size = [1024,1024] #specifies the number of pixels and lines for the output image file
res = [15,15]
create_channels = [7,1,2,5] #creates 7 8bit, 1 16bit signed, 2 16bit unsigned and 5 32bit real channels
data_layout = "PIXEL" #Pixel interleaved

cim(new_file, "", "", file_size, res, create_channels, data_layout)

Add or delete new channel to an existing .pix file

This recipe demonstrates how to quickly add a 8bit, 16bit unsigned, 16bit signed and or 32bit floating point channels to an existing .pix file. This can be very useful for when building custom models.

from pci.pcimod import pcimod

#Add new image channels to existing file
file = r"c:\data\image.pix"
channels = [4,0,3,1] #add 4 8bit, 0 16bit signed, 3 16bit unsigned and 1 32bit real channels

pcimod(file, "ADD", channels)

#delete image channel(s) from existing file
file = r"c:\data\image.pix"
channels = [1,4,6] #delete channels 1, 4 and 6

pcimod(file, "DEL", channels)

Copy image channels to an existing file with different projection

This recipe demonstrates how to copy an raster channel from one file to another with different projections. It requires that the user reproject the source image to the same projection and bounds as the destination image, create an empty channel in the destination file and finally, copy the pixels.

from pci.pcimod import pcimod
from pci.iii import iii
from pci.reproj2 import reproj2

source_file = r"c:\data\ndvi_1.pix"
destination_file = r"c:\data\ndvi_2.pix"

#Add a new channel with correct bit-depth to destination file
add_channel = [0,0,0,1]

pcimod(destination_file, "ADD", add_channel) #Adds a single 32 bit channel to the ndvi_2.pix file


#reproject the source channel to the same projection and extents of destination file

'''
Note: for now, it is required to know the projection information of the
destination file. Support will be added soon to automatically retrieve this projection
information. You can get the georeferencing information by running PROREP in terminal
'''

ndvi_channel = [5] #NDVI was calculated for this image and is stored in channel 5
reproj_source_file = r"c:\data\ndvi_1_temp_reproj.pix"
reproj_method = "BR" #Bounds and resolutions are unchanged, calculates pixels and lines
resolution = [2.0, 2.0]
map_units = "UTM 55 G D000"
top_left_x = "514418.000"
top_left_y = "5262616.000"
bottom_right_x = "527908.000"
bottom_right_y = "5246564.000"

reproj2(source_file, ndvi_channel, [], "", reproj_source_file, "", "",
        reproj_method, [], resolution, "NO", map_units, "", top_left_x,
        top_left_y, bottom_right_x, bottom_right_y, "", "")


#copy image channel
input_channel = [1]
output_channel = [6]

iii(reproj_source_file, destination_file, input_channel, output_channel, [], [])

Export rasters or vectors to foreign file format

This recipe demonstrates how to export rasters and vectors from the .pix format to a foreign file format, such as, .shp, .tif, etc.

from pci.fexport import fexport

#export image raster(s) to jpeg2000 format
pix_file = r"D:\kompsat-2.pix"
foreign_file = r"C:\kompsat-2.jp2"
channels = [1,2,3,4]
format = "jp2"
compression = "10" #result should be about 10% the size of the input image

fexport(pix_file, foreign_file, [], channels, [], [], [], [], format, compression)


#export vector layer
pix_file = r"c:\data\vector.pix"
vector_layer = [2]
format = "shp"

fexport(pix_file, foreign_file, [], [], [], vector_layer, [], [], format, "")

#Note you can perform fexport to convert from a foreign file format to a different foreign file format