Example: Create Two Images From One Table

More than one image can show data from the same table, including from the same tile field.

 

Consider an image that shows terrain elevations in a region of Florida, as shown in the Style: Palettes topic:

 

eg_style01_28.png

 

We can make multiple copies of that image and change the style applied to each.  In the Project pane we Copy the Florida image component and then Paste it a few times to create additional Florida 2, Florida 3 and Florida 4 images.   Being copies of the original Florida image these all will also take their data from the same table.  

 

We can then open each image in turn and launch the Style panel to change the palette used by that image.   Doing that only changes the style of display, a property of the image and not the data.   We make no changes to the data in the table.

 

eg_style01_29.png

Above we see all four images open in undocked windows in our Manifold desktop, each one using different Style settings.  They all show the same data from the same field in the same table, but present it in different ways.

 

To repeat, images contain no data themselves.  They only contain properties that specify from which table and field they should take data to display, and they contain properties that specify how to display that data.     We can exploit that capability to create images that can have Style or other characteristics that are editable even if the image takes its data from a read-only table.   For a detailed example, see the  Example: Style Applied to an Image Server Image topic.

See Also

Getting Started

 

User Interface Basics

 

Tables

 

Images

 

Style: Images

 

Style: Channels and Outputs Tutorial

 

Style: Autocontrast

 

Style: Palettes

 

Example: How Images use Tiles from Tables - An example showing how an image is made up from data stored in a table in tiles.

 

Example: An Image using Computed Fields in a Table - How an image can be created from tiles where the data for the tiles is taken from a field that is computed on the fly.

 

Example: Change the Contrast of an Image - In this example we use the Style panel to change the contrast of an image.

 

Example: Using the Assign Channels Button - The Assign Channels button in the Style panel for images allows us to assign channels to the standard three Red, Green, and Blue display outputs using frequently-desired arrangements.   The button provides a short cut way to assign all channels at once instead of doing each channel individually.

 

Example: Assign Channels - How to use the Style panel for images to assign channels to display outputs such as R, G, B or A.  This topic shows examples of channel combinations and the visual results.

 

Example: Set Image Transparency using Alpha - The A row in the Style panel allows us to specify what transparency we want to apply to the image, either by applying the same value for A for all pixels or by using one of the other channels to also control the A value.

 

Example: Autocontrast and Hill Shading Images using Style - This example shows how the Style panel can hill shade an image using the values of pixels as heights and generating shadows as if the Sun were located at the specified azimuth and altitude.   This capability is used most frequently with raster images to give an impression of three dimensionality in cases where the values of pixels represent terrain elevations.

 

Example: Style Applied to an Image Server Image - Because the Style panel simply changes the way an image is displayed and not the data, it can operate on read-only data served by various web servers such as WMS REST servers.    In this example we look at every detail of creating a data source using an image server and then manipulating the appearance of the display with Style.  We will connect to a WMS server that provides LiDAR data in various forms, including as terrain elevation.