Plane Plot in TOPCAT - PDF

Session 4 Plane plot by Marim Saad In this session we will study: 1. The definition of plane 2. Plane plot forms plot  Plane plot definition In TOPCAT (Tool for OPerations on Catalogues And Tables), a plane plot is a scatter plot. It displays the rela...

Session 4 Plane plot by Marim Saad In this session we will study: 1. The definition of plane 2. Plane plot forms plot  Plane plot definition In TOPCAT (Tool for OPerations on Catalogues And Tables), a plane plot is a scatter plot. It displays the relative positions of dots based on two coordinates, X and Y. The plane plot is considered the most basic type of plot in TOPCAT. It is commonly used for applications requiring two-dimensional graphs. Suitable for visualizing relationships between two variables or attributes in a dataset. Plot “forms”: Plot "forms" are instructions for shaping data representations on the plotting surface. They use positional data from a table to determine the shapes. The most common form, "Mark," places a marker at each data position. Each marker in the "Mark" form has a fixed size and shape. 1. Mark form The Mark form simply plots markers with a fixed shape and size.  1.1 shading mode Defines the basic color for plotting each data point’s shape. Many forms allow selection of a "Shading Mode" to control the actual color displayed. Shaded color is based on the chosen style color. Shading may also be influenced by: ❑Number of points at a location, ❑Additional data coordinates, ❑Other configuration details. Shading modes 1.1.1 Flat Mode The Flat shading mode simply colors points in the color selected by their style. It has no additional parameters or coordinates 1.1.2 Translucent Mode The Translucent shading mode applies a transparent version of the selected style color to shapes. Transparency level depends on: ❑ The number of overlapping points, ❑ The setting of the Transparency Level slider. Moving the slider to the right increase transparency. Unlike basic transparent mode, Translucent mode adjusts transparency based on point density. This setting generally remains effective even when zooming in and out. 1.1.3 Transparent shading mode The Transparent shading mode applies a transparent version of the selected style color to shapes. Transparency level is controlled by the Opaque Limit slider: Moving the slider to the left makes points fully opaque, similar to Flat mode. Moving the slider to the right increases transparency. A higher opaque limit requires more overlapping points to achieve a fully opaque color. Unlike Translucent mode, transparency in Transparent mode is fixed by the opaque limit and does not vary with point density.  1.1.4 Auto shading mode Auto shading mode colors isolated points in their selected color. When multiple points overlap, the color darkens to indicate density. For isolated points (common in non- crowded plots or outliers in crowded plots), it behaves like Flat mode. Provides an easy way to identify dense regions in the plot.  1.1.5 Density Mode In TOPCAT, Density shading mode is a way to show how crowded or dense areas of the plot are by using colors. Here’s how it works: Color for Density: It uses colors to show where points overlap. The more points that overlap in one spot, the darker or more intense the color. Pixel-Level Details: Each tiny spot (pixel) on the plot is colored based on how many points cover it. This is like Auto mode, but with more user-configurable options  1.1.5.1 Density Shader In TOPCAT, the Density Shader is a tool that lets you pick a color style for showing data density (how crowded the points are) on a plot. There is two types of Color Maps: Relative Maps Absolute Maps (marked with "*") These ignore the base color and These adjust the base color of your data, like apply a completely new color uses making it lighter or darker to show density levels. scheme based on density, making This keeps the original color you chose for each areas of high or low density stand dataset and just modifies it for density. out more on their own. For multiple datasets (when you’re comparing For a single dataset, absolute different groups of data), relative maps are helpful. maps are often clearer since they When to They adjust each dataset’s base color for density, fully highlight density. Use so you can still tell different datasets apart by their original colors. 1.1.5.2 Shader Flip Whether the density scale should map forwards or backwards into the color map.  1.1.5.3 Shader Quantise TOPCAT provides a possibility to adjust the number of different colors where a color map is applied to your plot. This feature is called ‘Shader Quantise’. Here’s what it is doing: Smooth to Stepped Colors: Usually, the color map is continuously changing. The more you increase Shader Quantise, the fewer colors are available, and instead of an even smoother gradient of colors there are stepped layers of colors.  1.1.5.4 Density Subrange In TOPCAT, Density Subrange lets you control which range of density values is shown in your color map. Here’s what it does: ❑Adjusting Density Range: By default, the colors cover the whole range of density values in the plot. The most crowded spots are automatically given the highest colors. ❑Using the Slider: With the Density Subrange slider, you can limit the range, making colors focus only on certain density levels. This can help highlight specific areas by ignoring very low or very high densities.  1.1.6 Aux Mode The Aux shading mode colors each point according to the value of an additional data coordinate. The point colors then represent an additional dimension of the plot. The shading is done using the shared color map. 1.1.6.1 Aux The auxiliary coordinate data values. Fill this in with a column name or expression from the table just like for a positional coordinate. 1.1.6.2 Opaque Limit Determines transparency of the points. By default, they are fully opaque, but if you slide the slider to the right, they will become progressively more transparent.  1.1.7 Weighted mode In TOPCAT, Weighted mode is a shading option that colors the plot points based on density (like Density mode) but adds a twist: it lets you apply a weighting factor to each point. Here’s how it works: ❑ Color by Density with a Weight: Similar to Density mode, this mode uses colors to show how crowded areas are. But here, each point can have a weight, which affects the final color intensity of that spot. The more weight a point has, the more it influences the color. ❑ Customizing the Weighting: You can choose how these weights are combined at each pixel, allowing for more control over the coloring than Density or Aux modes alone.  the Size form adds extra information to the plot by 1.2 size form varying marker sizes according to data values, helping you see patterns or differences based on that third dimension. 1.3 SizeXY The SizeXY form plots a shaped marker whose width Form and height vary independently according to two supplied data coordinates. The marker shape can thus encode two additional dimensions of the plot.  1.4 Vector Form The Vector form plots directed lines from the data position given delta values for the coordinates. The plotted markers are typically little arrows, but there are other options. 1.4.1 X Delta, Y Delta,... The coordinates of the changes in each coordinate which gives the vector. The coordinates here match the coordinates of the plot. 1.4.2 Arrow Arrow shape selected from a range of options. 1.4 XY ERROR X/Y Error The error along the horizontal and vertical directions, as column names or expressions. 1.5 Line Form Line form draws a point-to-point line joining up the points making up the data set. 1.6 Linear Fit In TOPCAT, the Linear Fit Form is a tool that draws a straight line on the plot to represent the general trend of the data.  1.7 Quantile Form In TOPCAT, the Quantile Form is a tool that draws a line showing a specific value level (quantile) within the data across the plot, helping you see patterns without the impact of extreme values Here’s how it works: Plotting a Quantile Line: A quantile is a value that marks a specific percentage in a data set. Smoothing Option: The line can be smoothed to reduce noise and make patterns clearer. This uses a “kernel” (a mathematical smoothing technique) with adjustable width to smooth out fluctuations and give a more continuous look. 1.6.1 Defines the quantile or quantile range of values that should be Quantiles marked in each pixel column (or row). The slider control goes from 0 (minimum in pixel column/row) to 1 (maximum in pixel column/row), so 0.5 indicates the median.  1.7 Label Form The Label form draws a text label by each point position.  1.8 Contour Form The Contour form (plots position density contours). These provide another way (alongside the Auto, Density and Weighted shading modes) to visualize the characteristics of over dense regions in a crowded plot.  1.8.1 Levels The actual values at which contours have been plotted. This can be useful for weighted plots using with a Combine value of mean, but for other combinations it may not have much physical meaning. 1.9 Fill Form If a two-dimensional dataset represents a single-valued function, the Fill form will fill the area underneath the function's curve with a solid color.  1.10 Grid Form The Grid form plots 2D point data aggregated into rectangular cells on the plot. Allows optional weighting for individual points. Configurable settings determine how values are combined to produce output pixel colors. Can be used for: ❑2D histograms, ❑Weighted density maps, ❑Gridded data plotting Thank you very much!