Automatic Coordinate Register System
Remote Sensing
Image registration is the process of transforming different sets of data into one coordinate system
Image registration is the process of transforming different sets of data into one coordinate system. Data may be multiple photographs, data from different sensors, from different times, or from different viewpoints1. It is used in computer vision, medical imaging, military automatic target recognition, and compiling and analyzing images and data from satellites. Registration is necessary in order to be able to compare or integrate the data obtained from these different measurements.
This program is designed to Small Format Aerial Photo Application. This process is to manipulate the ER Mapper Files (*.ers) using LISTRIG file (*.txt) in batch. After this process, you will have ER Mapper files which have an additional GCP inside generated from LISTRIG file, then you can rectify those files in batch using the automatic rectification wizard from ER Mapper.
How it works
The program reads every *.ers file in the input folder and pairs each one with a record from the LISTRIG text file, which holds the coordinates of the photo centre in degrees and minutes. For each photo it takes an *.ers header template, substitutes the extent, datum, projection and coordinate type, and writes a new *.ers file into the output folder. The half-width and half-height of the photo are converted from metres to degrees so the corner coordinates can be written as a bounding box around the centre point.
Source code
NoteVisual BASIC 6 - Automatic Coordinate Register System
'+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
' Automatic Coordinate Register System (ACRS)
'
' Batch-writes ER Mapper (*.ers) headers for small-format aerial
' photos, using photo-centre coordinates read from a LISTRIG file.
'
' Benny Istanto, February 2007
'+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Option Explicit
'--- Configuration -------------------------------------------------
' Adjust these to suit your own machine and data layout.
Private Const DEFAULT_LISTRIG_DIR As String = "C:\ACRS\listrig"
Private Const TEMPLATE_FILE As String = "file_temp.txt" ' *.ers header template
Private Const DATASET_TYPE_FILE As String = "data_temp.txt" ' DataSetType value
Private Const MAX_FILES As Integer = 1000
' Rough metres per degree of latitude. Used to convert the photo
' half-width and half-height into a degree offset from the centre.
Private Const METRES_PER_DEGREE As Double = 111000
'--- Module state --------------------------------------------------
Private m_ErsFiles(MAX_FILES) As String ' full path of each *.ers found
Private m_DataSetNames(MAX_FILES) As String
Private m_FileCount As Integer
'===================================================================
' Browse for the LISTRIG file
'===================================================================
Private Sub cmdBrowseListrig_Click()
On Error GoTo CancelledByUser
dlgFile.DialogTitle = "Open LISTRIG file"
dlgFile.FileName = ""
dlgFile.InitDir = DEFAULT_LISTRIG_DIR
dlgFile.Flags = cdlOFNFileMustExist Or cdlOFNPathMustExist
dlgFile.Filter = "Comma delimited file (*.txt)|*.txt|All files (*.*)|*.*"
dlgFile.FilterIndex = 1
dlgFile.ShowOpen
txtListrigFile.Text = dlgFile.FileName
CancelledByUser:
Exit Sub
End Sub
'===================================================================
' Build the *.ers headers
'===================================================================
Private Sub cmdProcess_Click()
Dim inputFolder As String
Dim outputFolder As String
Dim listrigFile As String
Dim templateFile As String
Dim dataTypeFile As String
Dim outputPrefix As String
Dim outputFile As String
Dim foundFile As String
Dim ersHeader As String ' the *.ers header being built
Dim templateBlock As String ' replacement for "RasterInfo End"
Dim dataSetType As String
Dim photoWidthM As Double ' photo footprint, metres
Dim photoHeightM As Double
Dim halfWidthM As Double
Dim halfHeightM As Double
Dim lonCentre As Double ' photo centre, decimal degrees
Dim latCentre As Double
Dim lonMin As Double ' bounding box, decimal degrees
Dim lonMax As Double
Dim latMin As Double
Dim latMax As Double
Dim degLon As Variant ' LISTRIG fields
Dim minLon As Variant
Dim degLat As Variant
Dim minLat As Variant
Dim spare1 As Variant
Dim spare2 As Variant
Dim spare3 As Variant
Dim spare4 As Variant
Dim datasetPath As String
Dim i As Integer
Dim j As Integer
Dim recordIndex As Integer
inputFolder = dirInput.Path
outputFolder = dirOutput.Path
listrigFile = txtListrigFile.Text
outputPrefix = "\" & txtOutputPrefix.Text
templateFile = App.Path & "\" & TEMPLATE_FILE
dataTypeFile = App.Path & "\" & DATASET_TYPE_FILE
'--- Collect every *.ers file in the input folder ---------------
m_FileCount = 0
foundFile = Dir$(inputFolder & "\*.ers")
Do While foundFile <> ""
m_FileCount = m_FileCount + 1
lstInput.AddItem foundFile
m_ErsFiles(m_FileCount) = inputFolder & "\" & foundFile
foundFile = Dir$
Loop
If m_FileCount = 0 Then
MsgBox "No *.ers files found in " & inputFolder, vbExclamation, "Nothing to do"
Exit Sub
End If
'--- Rotate the list by one position ----------------------------
' NOTE: this is the behaviour of the original 2007 program. Output j
' takes its dataset name from input j-1, wrapping the last file round
' to the front. Preserved as-is so the results stay reproducible.
For i = 1 To m_FileCount
If i = m_FileCount Then
m_DataSetNames(1) = m_ErsFiles(m_FileCount)
Else
m_DataSetNames(i + 1) = m_ErsFiles(i)
End If
Next i
prgProgress.Min = 0
prgProgress.Max = m_FileCount
'--- Build one *.ers header per photo ---------------------------
For j = 1 To m_FileCount
Open m_ErsFiles(j) For Input As #1 ' source *.ers
Open templateFile For Input As #2 ' header template
Open listrigFile For Input As #3 ' photo-centre coordinates
Open dataTypeFile For Input As #5 ' DataSetType value
outputFile = outputFolder & outputPrefix & j & ".ers"
Open outputFile For Output As #4
Input #1, ersHeader
Input #2, templateBlock
ersHeader = ReplaceToken(ersHeader, "RasterInfo End", templateBlock)
'--- Photo footprint, centred on the LISTRIG coordinate ------
photoWidthM = Val(txtPhotoWidth.Text)
photoHeightM = Val(txtPhotoHeight.Text)
halfWidthM = photoWidthM / 2
halfHeightM = photoHeightM / 2
ersHeader = ReplaceToken(ersHeader, "Xa", CStr(photoWidthM))
ersHeader = ReplaceToken(ersHeader, "Ya", CStr(photoHeightM))
ersHeader = ReplaceToken(ersHeader, "Xb", CStr(halfWidthM))
ersHeader = ReplaceToken(ersHeader, "Yb", CStr(halfHeightM))
ersHeader = ReplaceToken(ersHeader, "Dt", TextOrDefault(txtDatum.Text, "RAW"))
ersHeader = ReplaceToken(ersHeader, "Pj", TextOrDefault(txtProjection.Text, "RAW"))
ersHeader = ReplaceToken(ersHeader, "Ct1", TextOrDefault(txtCoordType.Text, "RAW"))
'--- Find record j in the LISTRIG file -----------------------
recordIndex = 0
Do While Not EOF(3)
Input #3, spare1, degLat, minLat, degLon, minLon, spare2, spare3, spare4
recordIndex = recordIndex + 1
If recordIndex = j Then
lonCentre = Val(degLon) + Val(minLon) / 60
latCentre = Val(degLat) + Val(minLat) / 60
lonMin = lonCentre - (halfWidthM / METRES_PER_DEGREE)
lonMax = lonCentre + (halfWidthM / METRES_PER_DEGREE)
latMin = latCentre - (halfHeightM / METRES_PER_DEGREE)
latMax = latCentre + (halfHeightM / METRES_PER_DEGREE)
ersHeader = ReplaceToken(ersHeader, "x1", Str(lonMin))
ersHeader = ReplaceToken(ersHeader, "x2", Str(lonMax))
ersHeader = ReplaceToken(ersHeader, "y1", Str(latMin))
ersHeader = ReplaceToken(ersHeader, "y2", Str(latMax))
ersHeader = ReplaceToken(ersHeader, "x3", Str(lonCentre))
ersHeader = ReplaceToken(ersHeader, "y3", Str(latCentre))
End If
Loop
Close #2
Close #3
'--- Point the header at the raster on disk ------------------
Input #5, dataSetType
datasetPath = Replace(inputFolder, "\", "\\", 1, -1, vbTextCompare) & "/" & _
DatasetName(m_DataSetNames(j), inputFolder)
ersHeader = ReplaceToken(ersHeader, "= ERStorage", "")
ersHeader = ReplaceToken(ersHeader, "DataSetType", dataSetType)
ersHeader = ReplaceToken(ersHeader, "apusan", datasetPath)
Print #4, ersHeader
Close #4
Close #5
Close #1
lstOutput.AddItem outputFile
prgProgress.Value = j
Next j
MsgBox "Process completed successfully.", vbInformation, "Success"
End Sub
'===================================================================
' Helpers
'===================================================================
' Case-insensitive token substitution, matching the original program.
Private Function ReplaceToken(ByVal Source As String, _
ByVal Token As String, _
ByVal Value As String) As String
ReplaceToken = Replace(Source, Token, Value, 1, -1, vbTextCompare)
End Function
' Strip the folder and the *.ers extension to leave the dataset name.
Private Function DatasetName(ByVal FullPath As String, _
ByVal Folder As String) As String
Dim s As String
s = Replace(FullPath, Folder & "\", "", 1, -1, vbTextCompare)
DatasetName = Replace(s, ".ers", "", 1, -1, vbTextCompare)
End Function
Private Function TextOrDefault(ByVal Value As String, _
ByVal Fallback As String) As String
If Trim$(Value) = "" Then
TextOrDefault = Fallback
Else
TextOrDefault = Value
End If
End Function
'===================================================================
' Folder / drive browsers
'===================================================================
Private Sub dirInput_Change()
filInput.Path = dirInput.Path
End Sub
Private Sub drvInput_Change()
dirInput.Path = drvInput.Drive
End Sub
Private Sub drvOutput_Change()
dirOutput.Path = drvOutput.Drive
End Sub