Evaluation window

When entering “Evaluation” window, the evaluation grid and the grid points available for evaluation are shown in the window. The position (X,Y) and gray value (G) of the image pixel pointed by the mouse arrow are shown on the upper left. The name of the background image is indicated on the upper left corner of the window. Following are descriptions of buttons, mouse functions and menus.

Evaluation points and flag value

Evaluation points are used to determine the center positions of interrogation windows. They are usually set at intersections of the regularly spaced vertical and horizontal grid lines. The evaluation points can also be set with an irregular grid structure or be arbitrarily distributed without a grid structure. A flag value is used for each point to determine the evaluation status as follows:

Flag value 0: The point is not selected for evaluation, so that it is not shown in the window;

Flag value 1: The point is selected for evaluation, so that it may be shown as a small bright cross;

Flag value 2: The point has a valid vector, so that it may be shown as a small red cross, and the vector may be displayed as a red arrow;

Flag value 3: The point has a vector to be deleted, so that the point is not shown in the window, but the deleted vector may be displayed as a white arrow;

Flag value 4: A temporal flag value that does not appear in the final results;

Flag value 5: The point has a corrected vector, so that the point is not shown in the window, but the corrected vector may be displayed as a pink arrow;

Flag value -2: The point (shown as yellow cross) is selected for a constant vector, i.e. it does not change in the iterated evaluation procedure, but it is used for window shifting and image correction. 

Buttons

Button image: Used to switch images displayed in the window;

Button G: Used to show or hide evaluation grid lines;

Button P: Used to show or hide evaluation points;

Button Vector: Used to show or hide particle image displacement vectors;

Button TJ”: Used to cancel menu or mouse functions;

Button Zoom”: Used to open dialogue window “Detail” for a closer view of image or vectors in a selected frame;

Button “+” becomes visible when a vector map displayed in the window. It is used to increase the length of the displayed vector;

Button “-” becomes visible when a vector map displayed in the window. It is used to decrease the length of the displayed vector;

Button “c” becomes visible when a vector map displayed in the window. The vectors will be centered at the evaluation points when it is pushed down;

Invisible button hide in the frame on the top left of the window is used to switch the displayed X and Y between image coordinate system (pixel) and physical coordinate system (mm).

Slider button

The slider button is used to change brightness of the displayed background image.

Mouse functions for general purpose

With following mouse functions the interrogation points can be selected or deleted, and a frame can be drawn for showing the detail.

Select interrogation points: Grid points (with flag value 0) in a rectangular region between two clicks of the left mouse button are selected as interrogation points and shown with bright, small crosses. After the first click of the left mouse button, bitmap button “TJ” is shown in the window. The mouse function can be canceled by pressing “TJ” button, and “TJ” button disappears when the mouse function is canceled. If you want to continue the mouse function, move the mouse arrow to a desired position with “TJ” button shown in the window, and click the left mouse button the second time.

Delete interrogation points or vectors: Interrogation points (with flag value 1) or evaluated vectors (with flag value 2) in a rectangular region selected with two right mouse clicks are deleted. The operation procedure is the same as that of selecting interrogation points, but right mouse button is clicked.

Draw a frame for showing the detail: By pressing and holding down the left mouse button, and moving the mouse arrow, a frame can be drawn in the window. After the frame is drawn, bitmap buttons Zoom and “TJ” are shown in the window. The frame and buttons are cleared by pressing the “TJ” button. When pressing Zoom button, the “Detail” window is opened to display the vectors and the background image in the selected frame.

Limit evaluation grid in a selected frame: By pressing left mouse button after a frame is drawn in the window. A regular grid structure is determined within the frame according to the grid width and height set in “Evaluation settings” window.

Mouse function for creating an irregular grid structure

This function is turned on with menu choice “Edit \ Grid structure \ Irregular”. When this function is on, the left mouse functions described above is inactivated. Clicking left mouse button at desired mouse arrow position in the digital image area allows you input this position as a corner point of a quadrangle in a dialogue box titled with “Irregular grid”. The grid line numbers can also be input in the dialogue box. When the four corners of the quadrangle are selected, an irregular evaluation grid structure is generated by pressing button “Create” in the dialogue box. The irregular grid can be expended in 4 directions to fit a complex flow boundary. This function is turned off by pressing button “Create” in the dialogue box or by pressing “TJ” button in “Evaluation” window.

Mouse function for selecting evaluation points without a grid structure

This function is turned on with menu choice “Edit \ No grid distribution \ Arbitrary”. When the function is on, an evaluation point can be added by pointing mouse arrow at desired position in the image and pressing left mouse button. This function is turned off by pressing “TJ” button.

Mouse functions for shifting evaluation grid and point

These following functions are turned on with menu choices and turned off by pressing “TJ” button.

Column shift function (Edit \ Grid/point shift \ Column): This function can be used to shift all the evaluation points in one column in two steps: (1) Point mouse arrow near to one of the evaluation points in the column and then click left mouse button; (2) Move mouse arrow to desired position of the selected evaluation point and then click left mouse button. 

Corner shift function (Edit \ Grid/point shift \ Corner): This function can be used to arbitrarily move one corner of the irregular evaluation grid in two steps: (1) Point mouse arrow near to the corner to be shifted and then click left mouse button; (2) Move mouse arrow to desired position and then click left mouse button. 

Individual point shift function (Edit \ Grid/point shift \ Point): This function can be used to arbitrarily move a selected evaluation point in two steps: (1) Point mouse arrow near to the evaluation point to be shifted and then click left mouse button; (2) Move mouse arrow to desired position and then click left mouse button. 

Row shift function (Edit \ Grid/point shift \ Row): This function can be used to shift all the evaluation points in one row in two steps: (1) Point mouse arrow near to one of the evaluation points in the row and then click left mouse button; (2) Move mouse arrow to desired position of the selected evaluation point and then click left mouse button. 

All points shift function (Edit \ Grid/point shift \ All): This function can be used to shift all the evaluation points in two steps: (1) Point mouse arrow near to one of the evaluation points and then click left mouse button; (2) Move mouse arrow to desired position of the selected evaluation point and then click left mouse button. 

Mouse function for select a image pattern

This function is turned on with menu choice “Tools \ Calibration markers \ Image pattern”. When the function is on, a frame of given size moves with the mouse arrow, and a left mouse button clicking select the raw image pattern in the frame. Then dialogue box “Image pattern for calibration marker search” is opened to determine the shape, angle, size, and intensity of the synthetic image pattern used for calibration marker search.

Mouse function for vector map group

When a group of vector maps of a regular evaluation grid is loaded in the evaluation window, a left mouse clicking function can be used to display temporal distributions (time history) of displacement components at a selected evaluation point. It requires hiding evaluation points and vectors by pressing down button “Point” and “Vector”. When clicking the right mouse button, the evaluation point nearest to the mouse arrow is selected. This function can be turned off by selecting menu “Edit \ Single PIT/IPT \ Data on/off”.

Buttons for PIV recording group and/or vector map group

Tow buttons, i.e. “<” and “>”, and an edit box are used to control the display of PIV recording group and vector map group. The edit box is used to show the number of current PIV recording or vector map. The current recording/vector number can be changed by directly inputting a number in the   edit box or pressing “<” or “>” button. When pressing “<” or “>” button, the current recording/vector number is decreased or increased with a skip number determined in the start window. 

Menu group “File”

File \ Load vector map - Used to load a saved vector map from a file into the current memory;

File \ Save BG image - Used to save the overlapped color image displayed in the background;

File \ Save data - Used to save current vector maps or other processed data into a file;

File \ Close - Used to close the evaluation window.

Menu “Edit \ Evaluation settings”

Used to open “Evaluation settings” window

Menu group “Edit – Vector map memory”

Edit \ Load vectors from \ M1 - Used to move vectors from Memory 1 to current memory;

Edit \ Load vectors from \ M2 - Used to move vectors from Memory 2 to current memory;

Edit \ Save vectors into \ M1 - Used to copy vectors from current memory to Memory 1;

Edit \ Save vectors into \ M2 - Used to copy vectors from current memory to Memory 2;

Menu groupEdit - Postprocessing”

Edit \ Vector interpolation \ with data in M0 - Used to interpolate vectors at selected points with current vectors in the 3x3 neighbourhood. This operation works at points with flag value 1;

Edit \ Vector interpolation \ with data in M1 - Used to interpolate vectors at selected points with vectors in Memory 1. This operation works at points with flag value 1;

Edit \ Vector interpolation \ with data in M2 - Used to interpolate vectors at selected points with vectors in Memory 2. This operation works at points with flag value 1;

Edit \ Vector operations \ General functions \ M0=M0-mean(M0(x,y)) - Used to subtract the averaged vector from current vector map. This operation works at points with flag value 2;

Edit \ Vector operations \ General functions \ M0=M0-mean(M0(t)) - Used to subtract the time mean vector map from the current vector map.

Edit \ Vector operations \ General functions \ M1=mean_x(M0) - Used to compute averaged vectors in the x-direction and save the results in M1;

Edit \ Vector operations \ General functions \ M2=mean_y(M0) - Used to compute averaged vectors in the y-direction and save the results in M2;

Edit \ Vector operations \ General functions \ M0=M0-M1 - Used to subtract vectors in Memory 1 from the current vector map, when the grid structures are the same. This operation works at points with flag value 2 for both M0 and M2.

Edit \ Vector operations \ General functions \ M0=M0-M2 - Used to subtract vectors in Memory 2 from the current vector map, when the grid structures are the same. This operation works at points with flag value 2 for both M0 and M2.

Edit \ Vector operations \ General functions \ M0=M0+M1 - Used to add vectors in Memory 1 to the current vector map, when the grid structures are the same; This operation works at points with flag value 2 for both M0 and M1.

Edit \ Vector operations \ General functions \ M0=M0+M2 - Used to add vectors in Memory 2 to the current vector map, when the grid structures are the same; This operation works at points with flag value 2 for both M0 and M2.

Edit \ Vector operations \ General functions \ M0=M0+S - Used to add a constant vector S to the current vectors.

Edit \ Vector operations \ General functions \ M0=S - Used to set a constant vector S to the selected evaluation points (with flag value 1).

Edit \ Vector operations \ Stereo functions \ M0=STEREO(M1,M2) - Used to reconstruct a 3-D vector map out of two 2-D vector maps saved in M1 and M2 for the left and right camera of a stereo PIV system, respectively;

Edit \ Vector operations \ Stereo functions \ M0=StereoA(M1) - Used to check target shifting data for camera A with vectors saved in M1;

Edit \ Vector operations \ Stereo functions \ M0=StereoB(M2) - Used to check target shifting data for camera A with vectors saved in M2;

Edit \ Vector filtering \ Irregular - Used to detect and remove erroneous vector according to the median vector determined in a window of selected size;

Edit \ Vector filtering \ Regular - Used to detect and remove erroneous vectors with 1-D, 2-D and 3-D median filter, to smooth vector maps with low-pass filter and to determine fluctuations of vector maps on the base of a regular grid structure;

Edit \ Single PIT/IPT \ Data on/off - Used to turn on/off display evaluation results of the single particle image tracking (PIT) or image pattern tracking (IPT). When the display is on, further processing of the results is possible.

Edit \ Single PIT/IPT \ Import data - Used to import data, e.g. test signals;

Edit \ Single PIT/IPT \ Postprocessing \ Fourier analysis (FFT) - Used to conduct a fast Fourier analysis on the single PIT/IPT results;

Edit \ Single PIT/IPT \ Postprocessing \ Fourier analysis (FT) - Used to conduct a direct Fourier analysis on the single PIT/IPT results;

Edit \ Single PIT/IPT \ Postprocessing \ Polynomial fit - Used to smooth the time histories with polynomial curve fit;

Edit \ Single PIT/IPT \ Postprocessing \ Gradient - Used to compute the gradient time history of the single PIT/IPT results;

Edit \ Single PIT/IPT \ FT peak search \ maximal X - Used to search for high peak of FT amplitude in x-direction.

Edit \ Single PIT/IPT \ FT peak search \ maximal Y - Used to search for high peak of FT amplitude in y-direction.

Edit \ Single PIT/IPT \ Coordinate rotation - Used to rotate the coordinate for adjusting x- and y-components of the displacements;

Edit \ Single PIT/IPT \ High/low-pass filter - Used to conduct a high- or low-pass filtering on the single PIT/IPT results;

Edit \ Single PIT/IPT \ Solid body angles - Used to determine solid body angles with data saved in M1 and M2;

Edit \ Single PIT/IPT \ Display limits - Used to change the start and end number of the displacement vectors displayed in the window;

Edit \ Single PIT/IPT \ Undo/redo - Used to undo or redo some of the latest data processing step for single PIT/IPT results;

Edit \ Single PIT/IPT \ Statistics - Used to conduct a statistical analysis on the single PIT/IPT results;

Edit \ Single PIT/IPT \ Rest - Used to undo all the data processing steps on the single PIT/IPT results;

Edit \ Single PIT/IPT \ Crop - Used to erase data that is out of the display limits;

Menu groupEdit - Evaluation grid/point”

Edit \ No grid distribution \ Particles \ PTV method - Used to set evaluation points on particle image centers determined with a complete particle image identification that is usually used for PTV;

Edit \ No grid distribution \ Particles \ LID method - Used to set evaluation points on particle image positions determined with a simple particle image identification that is usually used for individual particle image pattern tracking in LID recordings;

Edit \ No grid distribution \ Arbitrary - Used to turn on the mouse function for selecting evaluation points without a grid structure;

Edit \ No grid distribution \ Remove - Used to remove an evaluation point with a mouse click;

Edit \ No grid distribution \ Marker - Used to add an evaluation point to a selected marker;

Edit \ Grid reconstruction \ Horizontal channel \ Boundary mask #1 - Used to reconstruct the regular grid structure to fit a horizontal pipe flow according to the background mask image. The grid lines are adjusted so that they are almost parallel/perpendicular to the main flow direction at the entrance and outlet.  

Edit \ Grid reconstruction \ Horizontal channel \ Boundary mask #2 - Used to reconstruct the regular grid structure to fit a horizontal pipe flow according to the background mask image. The grid line distribution in the effective flow region are not changed, whereas the grid points outside are moved to the flow boundary.

Edit \ Grid reconstruction \ Horizontal channel \ Remove rows - Used to activate the mouse function for deleting horizontal grid lines.

Edit \ Grid reconstruction \ Horizontal channel \ Inset rows - Used to activate the mouse function for insetting horizontal grid lines.

Edit \ Grid reconstruction \ Cylinder outside \ Circle maximum - Used to reconstruct the regular grid structure to fit a solid body (i.e. a cylinder) in the image frame. It is required that the solid body has a simple shape and it’s image is completely included in the frame. The longitudinal grid lines start at the frame sides and go to the solid body with equal distances at the solid body boundary and the frame sides.

Edit \ Grid reconstruction \ Cylinder outside \ Circle minimum  - Used to reconstruct the regular grid structure to fit a solid body (i.e. a cylinder) in the image frame. It is required that the solid body has a simple shape and it’s image is completely included in the frame. The longitudinal grid lines start at the solid body boundary and stretch out to the frame side of minimal distance.

Edit \ Grid reconstruction \ Cylinder outside \ Fit frame - Used to reconstruct the regular grid structure to fit a solid body (i.e. a cylinder) in the image frame. It is required that the solid body has a simple shape and it’s image is completely included in the frame. The longitudinal grid lines start at the solid body boundary and stretch out to the frame side of maximal distance.

Edit \ Grid reconstruction \ Bended channel \ Pipe mask #1 - Used to reconstruct the regular grid structure to fit a pipe flow according to the background mask image. It is required that the pipe goes through the imaging frame with ends either on the left and right or on the top and bottom. The reconstructed grid has parallel lines in one direction. No-slip condition is setup for the evaluation.

Edit \ Grid reconstruction \ Bended channel \ Pipe mask #2 - Used to reconstruct the regular grid structure to fit a pipe flow according to the background mask image. It is required that one end of the pipe is at the left side of the frame, and another end at one of the other three sides. The reconstructed grid has no parallel lines. No-slip condition is setup for the evaluation.

Edit \ Grid reconstruction \ Circular channel - Used to reconstruct the regular grid structure to fit a circular channel flow according to the background mask image. It is required that the circular channel is completely included in the frame and the geometry should be simple enough. No-slip condition is setup for the evaluation, but it can be removed with menu function “Edit \ Select vectors”.

Edit \ Grid orientation \ x-x - Used to reverse the evaluation grid indices in horizontal direction;

Edit \ Grid orientation \ y-y - Used to reverse the evaluation grid indices in vertical direction;

Edit \ Grid orientation \ x/y - Used to switch the evaluation grid indices between horizontal and vertical direction;

Edit \ Grid/point shift \ Column - Used to turn on the mouse function for shifting evaluation points in a selected column;

Edit \ Grid/point shift \ Corner - Used to turn on the mouse function for shifting corners of a irregular evaluation grid;

Edit \ Grid/point shift \ Point - Used to turn on the mouse function for shifting a selected evaluation point;

Edit \ Grid/point shift \ Row - Used to turn on the mouse function for shifting evaluation points in a selected row;

Edit \ Grid/point shift \ All - Used to turn on the mouse function for shifting all the evaluation points;

Edit \ Grid structure \ Irregular - Used to turn on the mouse function for creating an irregular grid structure;

Edit \ Grid structure \ Append - Used to append current grid structure in selected direction;

Edit \ Grid structure \ Regular - Used to create a regular evaluation grid structure;

Edit \ Grid structure \ Coarse - Used to reduce the density of current evaluation grid structure;

Edit \ Grid structure \ Refine - Used to increase the density of current evaluation grid structure.

Menu groupEdit – Displacement vectors”

Edit \ Accept results \ valid + corrected - Used to accept both valid and corrected vectors as final results;

Edit \ Accept results \ valid only - Used to accept only valid vectors as final results, so that the corrected vectors are ignored;

Edit \ Accept results \ all - Used to accept all the vectors as final results including wrong vectors;

Edit \ Select vectors - Used to activate mouse functions to delete, freeze and restore displacement vectors at selected point, row and column.

Edit \ Clear all - Used to reset flags for the entire grid points to 1;

Edit \ Undo - Used to undo changes applied to the current vector map.

Menu group “View”

View \ Histogram \ x-displacement - Used to display the probability density distribution of the x component of the particle image displacement;

View \ Histogram \ y-displacement - Used to display the probability density distribution of the y component of the particle image displacement;

View \ Histogram \ z-displacement - Used to display the probability density distribution of the z component of the particle image displacement;

View \ Histogram \ rss of xyz - Used to display the probability density distribution of the root-sum-square value of the three particle image displacement components;

View \ Image filter - Used to show the effect of selected image filter;

View \ Contours - Used to create and display a contour map in the background image;

View \ Statistics- Used to display statistical analysis results of current vectors in a message box;

View \ Samples - Used to open “Test” window for viewing the evaluation samples;

View \ Pattern - Used to view the selected image pattern;

View \ Vectors- Used to select display of vector maps in the window;

View \ Frame - Used to draw a frame with known size using a mouse click;

View \ Data - Used to open “Data” window.

Menu group “Tools ”

Tools \ Image pattern tracking - Used to track an image pattern in high-speed video;

Menu group “Tools - Stereo/distorted image”

Tools \ Calibration markers \ Group distribution - Used to open dialogue box “Calibration maker distribution” and determine image/physical coordinates for searching a group of calibration markers;

Tools \ Calibration markers \ Individual search - Used to open mouse function for individual calibration marker search;

Tools \ Calibration markers \ Image pattern - Used to open mouse function for selecting an image pattern; 

Tools \ Calibration markers \ Group search - Used to start search for multiple calibration markers;

Tools \ Calibration markers \ View & edit - Used to view and editing data of grid markers for distorted PIV image calibration. A dialogue box named “Add and edit grid markers for image calibration” is opened with this menu choice.

Tools \ Calibration function \ Distorted coordinates - Used to display physical coordinates at the distorted image according to the calibration function;

Tools \ Calibration function \ Create function - Used to determine the calibration function of a selected camera according to the grid marker data;

Tools \ Calibration function \ Image effect - Used to test the effect of the selected calibration function;

Tools \ Calibration \ Stereo system - Used to calibrate the stereo system set parameters with the current vector map;

Tools \ Calibration \ Marker shift - Used to determine the image displacements of calibration markers resulting from the out-of-plane shift;

Tools \ Calibration \ Image pair - Used to calibrate the current recording pair (i.e. Reco.1 & Reco.2).

Menu group “Tools – Axis symmetrical BOS”

Tools \ BOS pre-processing \ Adjust grid - Used to shift and rotate regular interrogation grid to match the axis symmetrical flow field;

Tools \ BOS pre-processing \ Grid reset - Used to restore regular grid after evaluation on the adjusted interrogation grid;

Tools \ BOS pre-processing \ Refine - Used to adjust the symmetry of displacement vectors before reconstructing the density field;

Tools \ BOS reconstruction - Used to reconstruct axis symmetrical density field according to the background image displacement vectors;

Tools \ BOS export - Used to export BOS test results;

Menu group “Tools - Vector map group”

Tools \ Irregular to regular \ Interpolation - Used to interpolate vectors into a regular grid;

Tools \ Irregular to regular \ Local mean - Used to calculate local mean values of randomly distributed vectors at regular grid points;

Tools \ View time history - Used to view displacement time history at a selected point;

Tools \ Statistics - Used to conduct an statistical analysis of displacement vector maps to obtain information as mean values, Reynolds stresses and precision limits for uncertainty assessment;

Tools \ Filtering - Used to detect and remove erroneous vectors with 1-D, 2-D and 3-D median filter, to smooth vector maps with low-pass filter and to determine fluctuations of vector maps on the base of a regular grid structure;

Tools \ Binding - Used to bind a group of vector maps into one file.

Menu “Start”

Clicking menu “Start” executes an evaluation.

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