Although the system is able to export in various formats, it uses non-text files with the filename extension .cat. There are programs available (e.g. Convert5) to convert such files into tucson-format.
CDendro 7.3 and 7.5 built from 20 March 2012 is able to read most Catras formatted files. (7.4 and 7.5 before 20 March 2012 had an error which put the oldest data at the young end.)
- R. W. Aniol: Tree-ring analysis using CATRAS. Dendrochronologia 1:45–53 (1983)
- J. R. Pilcher: Sample Preparation, Cross-dating, and Measurement in: Methods of dendrochronology p.49, ISBN 978-0-7923-0586-6
- See list in Henri D. Grissino-Mayer's Ultimate Tree-Ring Web Pages: Software (at the end of the page).
Technical details of the Catras format
A Catras file could be read as a byte array i.e. as an array of 8-bit unsigned integers, meaning all with values in the range 0-255.
In the description below, the indexes of the array "arr()" goes from 0 to n-1 where n is the number of bytes within the file.
16-bit integer values are each stored as a pair of bytes. Certain parameters are stored at fixed index positions within the file. E.g.
Dim registeredRings As Integer = arr(45) * 256 + arr(44)
Also the year number of the oldest ring is stored at fix positions:
Dim firstYear As Integer = arr(54) + 256 * arr(55)
The actual ring width data is surrounded by ring width data with very high ring width values. Some times there are several such big ring width values both in the front and at the end of the series. The code below removes those "zero-data", though it may possibly represent zero-rings as measured from the heart of the sample and at the outer side of the sample.
Comments are stored using the old "IBM PC" character set.
The Catras file format is said to be able to store also information on latewood/earlywood, though to us the details of this are not known.
'Visual Basic .NET code (Visual Studio 2008). CDendro 2009-12-31 Private Function readCATRAS_File(ByVal fileName As String, ByRef ringWidthArr() As Single, ByRef lastYear As Integer, ByRef comment As String) As Boolean 'On return from this function ringWidthArr(1) contains the YOUNGEST ring width value. On Error GoTo atExit Dim arr() As Byte arr = My.Computer.FileSystem.ReadAllBytes(fileName) Dim veryFirstIx As Integer = 0 Dim veryLastIx As Integer = arr.Length - 1 Dim registeredRings As Integer = arr(45) * 256 + arr(44) Dim firstYear As Integer = arr(54) + 256 * arr(55) Dim ixOfFirstDataPair As Integer = 128 'data at index 128 and 129 is always 241, 216 - more such pairs may be there! It is also sort of an end signature Dim ixOfLastDataPair As Integer = ixOfFirstDataPair + (registeredRings - 1) * 2 'the address of the first member of a ring width pair If ixOfLastDataPair + 1 > veryLastIx Then Return False 'Find first non-zero ring Dim rWidth As Double, ring As Integer Dim ixOfCurrentPair As Integer Dim ixOfStartDataPair As Integer = ixOfFirstDataPair For ring = 0 To registeredRings - 1 ixOfCurrentPair = ixOfFirstDataPair + 2 * ring rWidth = (arr(ixOfCurrentPair + 1) * 256 + arr(ixOfCurrentPair)) / 100 If rWidth > 50 Then firstYear += 1 'ignore this zero ring Else ixOfStartDataPair = ixOfCurrentPair 'first non-zero ring width Exit For End If Next 'Check also for zero rings at the trailing end: Dim stopAdr As Integer = ixOfLastDataPair Dim adr As Integer For adr = ixOfLastDataPair - 12 To ixOfLastDataPair Step 2 'check 6 last widths, where the very last certainly is zero rWidth = (arr(adr + 1) * 256 + arr(adr)) / 100 If rWidth < 50 Then stopAdr = adr 'this is still a non-zero ring Else Exit For 'a zero ring found End If Next Dim rings As Integer = CInt((stopAdr + 1 - ixOfStartDataPair + 1) / 2) ReDim ringWidthArr(0 To rings) lastYear = firstYear + rings - 1 Dim targetWidthIx As Integer Dim targetAdr As Integer = ixOfStartDataPair For ring = 1 To rings targetWidthIx = rings - ring + 1 rWidth = (arr(targetAdr + 1) * 256 + arr(targetAdr)) / 100 If rWidth > 50 Then rWidth = 0 'handle too big values as zero value 2010-02-16 ringWidthArr(targetWidthIx) = CSng(rWidth) targetAdr += 2 Next comment = "" For k As Integer = 0 To 43 comment &= ibmPCToLatinChar(arr(k)) Next Return True atExit: End Function Dim latinVersion() As Char = Nothing Function ibmPCToLatinChar(ByVal b As Byte) As Char 'This conversion may not be complete Dim k As Integer If latinVersion Is Nothing Then ReDim latinVersion(0 To 255) For k = 0 To 255 latinVersion(k) = Chr(k) Next latinVersion(134) = "å"c latinVersion(132) = "ä"c latinVersion(148) = "ö"c latinVersion(129) = "ü"c latinVersion(130) = "é"c latinVersion(135) = "ç"c latinVersion(145) = "æ"c latinVersion(164) = "ñ"c latinVersion(143) = "Å"c latinVersion(142) = "Ä"c latinVersion(153) = "Ö"c latinVersion(154) = "Ü"c latinVersion(144) = "É"c latinVersion(128) = "Ç"c latinVersion(146) = "Æ"c latinVersion(165) = "Ñ"c End If Return latinVersion(b) End Function
Special thanks to Henri D Grissino-Mayer for help with understanding the Catras file format!/LÅL