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Code Examples

The MrSID Decode SDK includes code samples that demonstrate the use of the SDK's different interfaces.

The following C++ (.cpp) files are located in your examples/src directory.

Code example files and what they demonstrate
UserTutorial.cpp

Opening MG4 files

Using the PointIterator to access the point cloud

Using PointSource::read() to access a fixed number of points
DumpMG4Info.cpp

Accessing the point cloud properties

Displaying metadata
DecodeMG4ToTXT.cpp

Using a PointWriter class
IterateOverPoints.cpp 

Using a PointIterator

Accessing channel values from a PointData object

support.cpp

Using the FileIO class
UserTest.cpp Enables you to add your own test code to explore the SDK

Below, we walk through the UserTutorial.cpp example.

The following code opens an MG4 file:

FileIO *file = FileIO::create();
file->init("data/Tetons_200k.sid", "r");
MG4PointReader *pointSource = MG4PointReader::create();
pointSource->init(file);
file->release();

 

Now that the file is initialized, you can access the properties of the point cloud using the following code:

PointSource::count_type numPoints = pointSource->getNumPoints();
size_t numChannels = pointSource->getNumChannels();
const PointInfo &pointInfo = pointSource->getPointInfo();

printf("Number of points: %lld\n", numPoints);
printf("Number of channels: %lu\n", numChannels);
for(size_t i = 0; i < numChannels; i += 1)
   printf("Channel %lu: %s\n",  i,  pointInfo.getChannel(i).getName());

 

You can use either of the following two methods to access the point cloud. In the first, we use the PointIterator mechanism.

PointData buffer;
// create buffers for all the channels 1000 samples long
buffer.init(pointInfo, 1000);
// create an iterator of the whole point cloud with all the channels
PointIterator *iter = pointSource->createIterator(pointSource->getBounds(),
                                                  1.0,
                                                  pointInfo,
                                                  NULL);

size_t count;
// walk the iterator
while((count = iter->getNextPoints(buffer)) != 0)
{
   // do some thing with this chunk of the point cloud.
}
iter->release();

 

The second method extracts a fixed number of points (10,000 in this case):

PointData buffer;
{
   // only decode X, Y, Z
   PointInfo pointInfo;
   pointInfo.init(3);
   pointInfo.getChannel(0).init(*pointSource->getChannel(CHANNEL_NAME_X));
   pointInfo.getChannel(1).init(*pointSource->getChannel(CHANNEL_NAME_Y));
   pointInfo.getChannel(2).init(*pointSource->getChannel(CHANNEL_NAME_Z));
   buffer.init(pointInfo, 10000);
}

pointSource->read(Bounds::Huge(), buffer, NULL);
// do some thing with the points

 

Now we'll do a little housecleaning. When you're done with your point source, you should release it:

pointSource->release();
pointSource = NULL;