Thermalyze Operation


Overlay

The topics in this section explain how to create and use a graphic or drawing as a thermal image overlay to help locate hot spots and thermal artifacts.

 
 

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Controls

Description

An overlay is a graphic, drawing, or thermal image of a device that can be superimposed over or merged with the device's thermal image.  Overlays enable you to quickly locate areas on a device that correspond to hot spots and thermal gradients or anomalies displayed on the thermal image.  Pixels in the thermal image within a specific temperature range replace corresponding pixels in the overlay.  Overlay controls are located in the Overlay panel (see Figure 1) to the right of the Main Image.

Figure 1: Overlay panel

ON/OFF
Press this button to display or hide the overlay.
Max and Min Levels
Drag the max and min trackbar handles to determine the temperature range of thermal image pixels that replace corresponding pixels in the overlay.  Units are percentage of thermal image temperature range.  Thermal image temperature range is calculated by subtracting the minimum pixel value in the thermal image from the maximum.

Tip: You can also hover over the trackbar and use the mouse scroll wheel to change the value.
Set Thermal Overlay
Click this button to  transfer the currently displayed thermal image to the Overlay window where it can be used as the overlay for the Main Image.

Window

Description

The Overlay window (see Figure 2) allows images and schematics to be aligned with the device's thermal image so that thermal anomolies and gradients can quickly be located.  Overlays can be manually flipped, rotated, and shifted.  They can also be automatically sized, positioned, and rotated so that features on the overlay correlate positionally with the same feature the thermal image.

To open the Overlay window, select the Overlay item from the Test Tools menu or press the  button in the Test Tools section of the Shortcuts menu.

Figure 2: Overlay window

File

 Open Overlay
Click this button to open the Open Overlay dialog.  Image files with the following extensions can be opened: ".bmp", ".jpg", "png", and ".tif".

Note: The file name of the most recent overlay file opened or saved is displayed at the bottom of the Overlay window.
 Save Overlay
Click this button to open the Save Overlay dialog.  Image files with the following extensions can be saved: ".bmp", ".jpg", "png", and ".tif".  When saving an overlay, the file name that you provide is appended with ".bmp" unless another extension is included in the file name.  Overlays files are saved in the "Optotherm\Thermalyze\Overlays" folder, unless a different folder is selected.
 Clear Overlay
Clears the current overlay.
Export Window
The Overlay window can be saved to file in the following formats: bmp, jpg, png, and tif.  The size of the exported image is proportional to the size of the Overlay window.

Note: Exported Overlay windows are saved in the "Optotherm\Thermalyze\Export" folder unless you specify a different folder.
Print
Print the Overlay window.

Note: You must have a printer connected to your computer.
Print with Preview
Select this menu item to open the Print Preview dialog before printing.

Setup

 Get Thermal Image
Click this button to set the currently displayed thermal image as the current overlay.  The button labeled "Set Thermal Overlay" located in the Overlay panel to the right of the Main Image has identical functionality of the Get Thermal Image button.

High-contrast thermal overlays can often be created by increasing the temperature of the target in order to accentuate the emissivity differences of various surfaces.  Common methods of increasing target temperature include using the Thermal Stage for small devices or a heat gun for larger devices and circuit boards.

Tip: Use the Grayscale or Temperature color palettes to create a thermal overlay with high detail.
 Get Video Image
Click this button to set the currently displayed video image from the Video Camera window as the current overlay.
 Overlay Settings
Click this button to display the Overlay Settings window.
 Large Image Size
Press this button to display the overlay in full size, unpress for reduced size.

Zoom

 Zoom In

 Zoom Out

 Zoom Out Full

Zoom Level

 Pan

 Crop

Regions

Select
Select this button to position, resize, and rotate Regions.
Point
Select this button and then click on the overlay to create a Point Region.
Line
Select this button and then click and drag on the overlay to create a Line Region. 
Polyline
Select this button and then click on the overlay to to locate the first vertex of the Polyline Region.  Click to locate each vertex and then right-click on the last vertex to complete the polyline.
Invert Region Color
The default color of an unselected Region is white.  If Regions are difficult to distinguish from lite background colors, press this button to set the unselected Region color to black.
Delete Region
Click this button to delete the Region.

Align

 Automatic Alignment
Click this button to automatically resize, rotate, and shift the overlay so that the 3-sided Polyline Region on the overlay matches the corresponding Region on the thermal image.

Tip: Automatic alignment should be used when the same features can easily be identified on both the overlay and thermal image.
 Manual Alignment
Click this button to open the Manual Overlay Alignment window.

Tip: Manual alignment should be used when an inadequate number of features can be identified on both the overlay and thermal image for automatic alignment to be used.

Flip

 Flip Horizontally
Press this button to flip the overlay horizontally.
 Flip Vertically
Press this button to flip the overlay vertically.

Rotate

 Rotate Counter-Clockwise
Click this button to rotate the overlay counterclockwise.  In order to rotate the overlay, a single Point or Line Region must exist on the overlay to identify the point around which to rotate the overlay.  When a Line Region is used, the overlay is rotated around the start point.

Tip: Overlay rotation is typically used after automatic alignment procedures for fine tuning overlay alignment.

Tip: Rotation can degrade overlay quality.  Therefore, to maintain high overlay quality, minimize the number of rotation procedures.  A rotation procedure comprises pressing the rotation buttons (once or multiple times) and then pressing a non-rotation button to set the overlay rotation.
 Rotate Clockwise
Click this button to rotate the overlay clockwise.
Rotation Increment
Select the angle increment to rotate the overlay each time a rotate button is clicked.

Shift

 Shift Left
Click this button to shift the overlay left one pixel.

Tip: Overlay shifting is typically used after automatic alignment procedures for fine tuning overlay alignment.

Tip: Shifting can crop the overlay.  Therefore, to minimize unnecessary cropping, minimize the number of shift procedures.  A shift procedure comprises pressing the shift buttons (once or multiple times) and then pressing a non-shift button to set the overlay shift.
 Shift Right
Click this button to shift the overlay right one pixel.  
 Shift Up
Click this button to shift the overlay up one pixel.  
 Shift Down
Click this button to shift the overlay down one pixel.  
Shift Increment
Select the number of pixels to shift the overlay each time a shift button is clicked.

Undo Controls

 Undo Changes
Click this button to replace the current overlay with the Undo overlay and store the current overlay into memory as the Redo overlay.
 Redo Changes
Click this button to replace the current overlay with the Redo overlay.
 Set Undo Overlay
Click this button to store the current overlay into memory as the Undo overlay.

Note: When an overlay is opened from file, it is automatically stored into memory as the Undo overlay.

Status Bar

The pixel size of the current overlay is displayed at the bottom of the window.

Settings

Description

To open the Overlay Settings window (see Figure 3), select the Settings item under the Setup menu on the Overlay window or press the  button in the Setup section on the toolbar.

Figure 3: Overlay Settings window

Max Resolution
Select the maximum resolution of an overlay.  When an overlay is opened, if it has horizontal or vertical resolution greater than this setting, then the overlay resolution is reduced to this resolution.  To obtain optimal overlay clarity, select a resolution setting (if possible) that is equal to or greater than the resolution of the overlay file that will be opened.

Tip:  When a higher Max Resolution is selected, the current overlay in memory is converted to the new resolution.  Therefore, to maintain optimal overlay clarity, re-open the overlay file so that the original overlay file is converted to the higher resolution.

Note:  Higher resolution overlays require longer times to process and align.

Manual Alignment

Description

Click the Manual Overlay Alignment button  on the top toolbar of the Overlay window to open the Manual Overlay Alignment window (see Figure 4).  This window enables the measurement of overlay pixel size and can automatically resize, rotate, and shift the overlay to match the thermal image.

Few Features: Manual overlay alignment should be used when an inadequate number of features can be identified on both the overlay and thermal image for automatic alignment to be used.

Figure 4: Manual Overlay Alignment window

Thermal Image

Pixel Size
Enter the dimensions of each thermal image pixel in object space.  Object space represents real dimensions on the target object.  Pixel size depends on the camera lens installed and working distance.  Microscopic lenses have a fixed working distance and so their pixel size is constant.  For example, the 20 micron lens has a pixel size of 20 microns.

Tip: Measuring thermal image pixel size for a focusable lens can be accomplished by drawing a Line Region along an object in the thermal image that has a known length and then dividing that length by the number of pixels in the region.
Get from Lens [microns]
Press this button to obtain the thermal image pixel size based on the current lens installed.

Note: The thermal image pixel size cannot be obtained in this way for a focusable lens as pixel size depends on working distance.

Overlay

Pixel Size
If known, enter the dimensions of each overlay pixel in object space.  Object space represents real dimensions on the target object. 
Line Length
Enter the distance in object space between the end points of the Line Region drawn on the overlay.
Calculate from Line Length
Click this button to calculate the overlay pixel size by dividing Line Length by the number of pixels in the Line Region.

Note: A line Region must exist on the overlay before the overlay pixel size can be calculated.

Alignment

Align Overlay to Point
Click this button to automatically resize and shift the overlay so that the point Region on the overlay aligns with the corresponding point Region on the thermal image.

Note: The overlay may need to be manually rotated to match the thermal image.
Align Overlay to Line
Click this button to automatically resize, rotate, and shift the overlay so that the Line Region on the overlay aligns with the corresponding line Region on the thermal image.

Alignment

Initial Setup

  1. Open the Overlay window by selecting the  button in the Test Setup section of the Shortcuts toolbar.

  2. Open the Overlay Settings window and set Overlay Resolution to a minimum of 1280 x 960.

  3. Open the overlay file that corresponds to the device under test.

  4. If necessary, use the  and  buttons to flip the overlay to match the overlay orientation to the thermal image.

  5. Delete all existing regions by pressing the Delete All Regions button  on the Regions toolbar below the Main Image.

Automatic Alignment

Many Features: Automatic alignment should be used when the same features can easily be identified on both the overlay and thermal image.

  1. On the Region toolbar below the Main Image, select the Polyline Region button  and draw one (and only one) three-sided Polyline Region on the thermal image.  Position it so that it aligns with distinct features of the device such as corners, edges, or through-holes.  Features should be chosen so that the Region's three lines are at right angles to each other (i.e., forming three sides of a rectangle) and so that the four points making up the Polyline Region represent the four vertices of a rectangle.

  2. On the top toolbar in the Overlay window, select the Polyline Region button  and draw a three-sided Polyline Region on the overlay.  Position it so that the four points of the Polyline Region align with the same features as the four points on the thermal image.  Use the overlay Zoom and Pan tools for precise placement of Region vertices.

  3. Press the Automatic Alignment button .

Manual Alignment

Few Features: Manual alignment should be used when an inadequate number of features can be identified on both the overlay and thermal image for automatic alignment to be used.

Determine Thermal Image Pixel Size
  1. Open the Manual Overlay Alignment window.

  2. If the currently installed lens is a fixed-focus lens, press the Get from Lens [microns] button to obtain the thermal image pixel size.

  3. If the currently installed lens is a focusable lens, draw a Line Region along an object in the thermal image that has a known length and then divide that length by the number of pixels in the region.  Enter the calculated value in the Thermal Image Pixel Size box.

Determine the Overlay Pixel Size
  1. If the overlay pixel size is known, enter it in the Overlay Pixel Size box.

  2. If the overlay pixel size is not known, on the top toolbar in the Overlay window, select the Line Region button  and draw a Line Region on the overlay.  Position the start and end points with a distinct feature of the device whose length is known or can be determined.  Use the overlay Zoom and Pan tools for precise placement of start and end points.

  3. Enter the length of the feature in the Overlay Line Length box in units of microns and then press the Calculate from Line Length button.

Align to Point
  1. Delete all existing Regions by pressing the Delete All Regions button  on the Regions toolbar below the Main Image.

  2. On the Region toolbar below the Main Image, select the Point Region button  and draw one (and only one) Point Region on the thermal image so that it aligns with a distinct feature of the device.

  3. On the top toolbar in the Overlay window, select the Point Region button  and draw a Point Region on the overlay.  Position it so that it aligns with the same feature as on the thermal image.  Use the overlay Zoom and Pan tools for precise placement of the Region.

  4. Press the Align to Point button to automatically resize and shift the overlay to match the thermal image.

Align to Line
  1. Delete all existing Regions by pressing the Delete All Regions button  on the Regions toolbar below the Main Image.

  2. On the Region toolbar below the Main Image, select the Line Region button  and draw one (and only one) Line Region on the thermal image so that its start and end points align with a feature edge.  Note: the exact position of the end point is not important as it is only used for rotation angle.

  3. On the top toolbar in the Overlay window, select the Line Region button  and draw a Line Region on the overlay.  Position it so that the start point aligns with the same feature as the start point on the thermal image and the end point is positioned along the same feature edge.  Note: the exact position of the end point is not important as it is only used for rotation angle.  Use the overlay Zoom and Pan tools for precise placement of the Region.

  4. Press the Align to Line button to automatically resize, rotate, and shift the overlay to match the thermal image.

Fine Tune Alignment
  1. Use the Shift buttons , and  to correct for any remaining offset between the overlay and thermal image.

  2. Use the Rotate buttons  and  to correct for any remaining rotation misalignment between the overlay and thermal image.