Question

我正在尝试从文件中读取LAS File 1.3标头。

在我看过的每一个标题中，我希望阅读的第一件事是格式签名，它始终是“LASF”。

当我尝试阅读文件时，我所看到的只是“Ì”，“Ì”，“Ì”，“Ì”，“Ì”，“Ì”，“Ì”，“

我知道标题大小是227，我甚至试图从文件中直接读取227的长度，但我仍然没有阅读我应该阅读的内容。我希望这是有道理的。

这是我尝试过的：

typedef struct Header
{
    char File_Signature[4]; 
    USHORT SourceID;
    USHORT Reserved1;
    UINT GUID1;
    USHORT GUID2;
    USHORT GUID3;    
    char GUID4[8];        
    BYTE VersionMajor;        
    BYTE VersionMinor;
    char SystemID[32];        
    char GeneratingSoftware[32];        
    USHORT DOY;        
    USHORT YEAR;        
    USHORT HeaderSize;    
    UINT PointOffset;    

    INT NumberOfVariableLengthRecords;    
    BYTE PointDataFormatID;    
    USHORT PointDataRecordLength;    
    INT NumberOfPointRecords;    
    UINT NumberofPointsByReturn1;    
    UINT NumberofPointsByReturn2;    
    UINT NumberofPointsByReturn3;    
    UINT NumberofPointsByReturn4;    
    UINT NumberofPointsByReturn5;

    double XScaleFactor;    
    double YScaleFactor;    
    double ZScaleFactor;    
    double Xoffset;    
    double Yoffset;    
    double Zoffset;    
    double MaxX;    
    double MinX;    
    double MaxY;        
    double MinY;        
    double MaxZ;        
    double MinZ;
} LasHeader;




void OpenLasFile()
{

    //THIS DOES NOT WORK
    char buffer[227];
    ifstream myFile ("C:\atlass\area_cov.las");
    myFile.read (buffer, 227);


    //NOT WORK, TRIED THIS TOO
    ifstream input_file("C:\atlass\area_cov.las", ios::binary);
    LasHeader header;

    input_file.read((char*)&header, sizeof(header));   
    input_file.close();


    //ALL DATA OUTPUT'ed ARE 'ÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌ'
}

这是我正在尝试阅读的文件中的二进制块。

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

我的问题是：为什么我在阅读垃圾值，我做错了什么？

-------------------- UPDATE --------------------------

我测试了这个并且它有效，所以读取文件一定是个问题，任何人都可以帮忙吗？

有效的是：

unsigned char rawData[552] =
{
    0x4C, 0x41, 0x53, 0x46, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x02, 0x00, 0x03, 0x00, 
    0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x01, 0x02, 0x41, 0x74, 0x6C, 0x61, 0x73, 0x73, 
    0x20, 0x41, 0x74, 0x6C, 0x61, 0x73, 0x43, 0x6F, 0x72, 0x65, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 
    0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x41, 0x74, 0x6C, 0x61, 0x73, 0x43, 
    0x6F, 0x72, 0x65, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 
    0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x1E, 0x01, 0xDC, 0x07, 0xE3, 0x00, 
    0xE3, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x1C, 0x00, 0x14, 0x01, 0x2F, 0x00, 0x14, 
    0x01, 0x2F, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
    0x00, 0x00, 0x00, 0xFC, 0xA9, 0xF1, 0xD2, 0x4D, 0x62, 0x50, 0x3F, 0xFC, 0xA9, 0xF1, 0xD2, 0x4D, 
    0x62, 0x50, 0x3F, 0xFC, 0xA9, 0xF1, 0xD2, 0x4D, 0x62, 0x50, 0x3F, 0x00, 0x00, 0x00, 0x00, 0xB0, 
    0x53, 0x20, 0x41, 0x00, 0x00, 0x00, 0x00, 0x24, 0xFF, 0x53, 0x41, 0x00, 0x00, 0x00, 0x00, 0x00, 
    0x00, 0x00, 0x00, 0xE7, 0xB3, 0xFA, 0x83, 0x88, 0xA9, 0x20, 0x41, 0x1B, 0x56, 0x11, 0xE9, 0xBC, 
    0x1B, 0x20, 0x41, 0x77, 0x10, 0xD2, 0x7C, 0x27, 0x11, 0x54, 0x41, 0x14, 0xA5, 0xEC, 0x80, 0x7E, 
    0xF4, 0x53, 0x41, 0xC5, 0x20, 0xB0, 0x72, 0x68, 0x5D, 0x68, 0x40, 0x37, 0x89, 0x41, 0x60, 0xE5, 
    0xD0, 0x12, 0xC0, 0x21, 0xBE, 0x92, 0xFF, 0x06, 0x66, 0x17, 0x01, 0xA9, 0x60, 0x00, 0x00, 0xD8, 
    0x03, 0xC9, 0x02, 0xE2, 0x00, 0x01, 0x00, 0xAC, 0x71, 0x36, 0xBD, 0xE3, 0x25, 0x04, 0x41, 0x37, 
    0xB9, 0x92, 0xFF, 0x77, 0x58, 0x17, 0x01, 0xD7, 0x60, 0x00, 0x00, 0xE2, 0x0A, 0xC9, 0x02, 0xE2, 
    0x00, 0x01, 0x00, 0x4B, 0x90, 0x11, 0x90, 0xE3, 0x25, 0x04, 0x41, 0x00, 0xBF, 0x92, 0xFF, 0x98, 
    0x3A, 0x17, 0x01, 0x2B, 0x62, 0x00, 0x00, 0x23, 0x0A, 0x49, 0x02, 0xE4, 0x00, 0x01, 0x00, 0xBF, 
    0xF5, 0x61, 0xBD, 0xE3, 0x25, 0x04, 0x41, 0x1A, 0xBD, 0x92, 0xFF, 0x30, 0x11, 0x17, 0x01, 0xE4, 
    0x62, 0x00, 0x00, 0xDF, 0x08, 0x49, 0x02, 0xE4, 0x00, 0x01, 0x00, 0xF8, 0x6E, 0xF3, 0xA6, 0xE3, 
    0x25, 0x04, 0x41, 0x01, 0xBE, 0x92, 0xFF, 0x67, 0xE7, 0x16, 0x01, 0x83, 0x63, 0x00, 0x00, 0xCB, 
    0x06, 0x49, 0x02, 0xE5, 0x00, 0x01, 0x00, 0x0B, 0xF3, 0x1E, 0xA7, 0xE3, 0x25, 0x04, 0x41, 0xF2, 
    0xBB, 0x92, 0xFF, 0x99, 0xD9, 0x16, 0x01, 0x6D, 0x63, 0x00, 0x00, 0x03, 0x09, 0x49, 0x02, 0xE5, 
    0x00, 0x01, 0x00, 0x82, 0x1C, 0x94, 0x90, 0xE3, 0x25, 0x04, 0x41, 0xFA, 0xBE, 0x92, 0xFF, 0x98, 
    0xBE, 0x16, 0x01, 0x13, 0x63, 0x00, 0x00, 0xFF, 0x08, 0x49, 0x02, 0xE5, 0x00, 0x01, 0x00, 0xE5, 
    0xF0, 0x49, 0xA7, 0xE3, 0x25, 0x04, 0x41, 0xEE, 0xBC, 0x92, 0xFF, 0xDE, 0xB0, 0x16, 0x01, 0x04, 
    0x63, 0x00, 0x00, 0x8E, 0x0B, 0x49, 0x02, 0xE5, 0x00, 0x01, 0x00, 0x95, 0xA0, 0xBF, 0x90, 0xE3, 
    0x25, 0x04, 0x41, 0xD2, 0xBD, 0x92, 0xFF, 0x19, 0x88, 0x16, 0x01, 0xA9, 0x63, 0x00, 0x00, 0xD1, 
    0x08, 0x49, 0x02, 0xE7, 0x00, 0x01, 0x00, 0xA7, 0x24, 0xEB, 0x90, 0xE3, 0x25, 0x04, 0x41, 0xA8, 
    0xBE, 0x92, 0xFF, 0x29, 0x64, 0x16, 0x01, 0x97, 0x63, 0x00, 0x00, 0xFD, 0x04, 0x49, 0x02, 0xE7, 
    0x00, 0x01, 0x00, 0xC4, 0xF0, 0x11, 0x91, 0xE3, 0x25, 0x04, 0x41, 0x79, 0xD0, 0x92, 0xFF, 0xD0, 
    0x70, 0x17, 0x01, 0x30, 0x61, 0x00, 0x00, 0x60, 0x02, 0xC9, 0x02, 0xE2, 0x00, 0x01, 0x00, 0x91, 
    0x65, 0xC1, 0x44, 0xE4, 0x25, 0x04, 0x41, 0x12, 0xC7, 0x92, 0xFF, 0x02, 0x5E, 0x17, 0x01, 0x79, 
    0x61, 0x00, 0x00, 0x79, 0x05, 0xC9, 0x02, 0xE2, 
} ;


LasHeader test;

memcpy(&test, rawData, sizeof(test));

Answer 1

问题在于：

    ifstream myFile ("C:\atlass\area_cov.las");

反斜杠是C字符串中的一个特殊字符，形成escape sequences。在这种特殊情况下，\a被bell character（0x0B）取代，因此它正在尝试打开错误的路径并失败。

相反，您需要通过加倍来转义路径中出现的所有反斜杠：

    ifstream myFile ("C:\\atlass\\area_cov.las");

从流中读取结构或者字节而不是

1 个答案: