The Live View Elevation Tab

*Live View is available in all license levels of LP360.

The Elevation tab is very similar to the Intensity tab and its functions except values represent elevation rather than intensity. 

This control allows you to do two different actions (which can be combined):

• Turn points on or off based on their elevation values

• Colorize bands of elevation to a user defined solid color

Elevation Display in LP360

LP360 supports two basic elevation display modes:

• Elevation Gradient – Maps elevation values to a gradient color ramp (a color and a greyscale ramp are currently available)
• Elevation Color Bands – Maps elevations to a set of repeating colors

These two modes are selected from the Display selector on the main toolbar.  The selection of Gradient display along with the result is shown below.

The selection of Color Band display along with the result is shown below.

Most special display modes for elevation such as adding color bands are used in gradient mode since the effect is often lost in the color band display mode.  As noted later under Symbology, you can set the elevation ramp to greyscale to enhance the effect of adding colorization.

Overview of the Live View Elevation Tab

Adding Rows

There are three ways to add filter rows to the Elevation tab. 

Manually Add/Edit Rows

Pressing the Add Row button with no current rows selected invokes the Elevation Range dialog.

The fields of this dialog are:

• Name – This field allows you to name the range for easy reference.  For example, you could name the range “Low Areas.”
• Range Options:
  • Below – This will set a range from the minimum (zero) to the value you key in.  The Min value in the resultant row will read “Min”
  • Above – This will set range from the value you key in to the maximum elevation.  The Max value in the row will read “Max.”
  • Between – Allows you to key in both the minimum and maximum elevation values for this row.  Note that you can key in “Min” (case insensitive so min, mIn, miN etc. are all equivalent) for the low value and/or “Max” for the high value. 
  • [  ] Clip – This is disabled for direct key-in (it is used for data sampling)
• Color – Color sets how you want this range displayed.  There are two options
• • Color Ramp – Use the current color ramp that is set for this filter.  This is set using the Symbology tool.  It defaults to the typical color ramp expected for Elevations.
  • Solid Color – this selector allows you to display the band as a solid color rather than a color ramp.  For example, if your range is 10-20 and you set this to solid color, red then all points with an Elevation value between 10 and 20 inclusive will display as red. 

You can press the Apply value to see the effect of the current settings without dismissing this dialog. 

Adding a Row by Sampling

Pressing the eyedropper tool allows you to add a row by sampling the Map View. When you press the eyedropper tool, the cursor will change to a cross symbol while it is over the map view. Digitize a polygon around the area that you wish to sample. Note that only points that are currently being displayed will be sampled (“what you see is what you get”). The polygon is digitized by left-clicking each intermediate vertex and then double-clicking the final vertex. Note that if you sample a large area, the system can take some time to display the Symbology dialog.

After sampling, you will be presented with the Symbology dialog discussed in the previous section but this time with the “Between” fields populated . For example, in the sampling shown below, the sampled point elevation ranged from 185.182 to 205.118 (the units are the same as the Map View – in our example, meters).

You can future restrict this range by a standard deviation-based clipping value. The default is 1 standard deviation (1 “sigma”). This tends to reduce the impact of outliners. Uncheck the Clip box if you do not want clipping applied or change the multiplier if you want something other than the default of 1.0.For example, you can impose a less narrow clipping by using a value such as 1.5 as the standard deviation multiplier As you apply various clipping values, you will see the range value change.

An example of sampling a low area, using a 1.0 sigma clipping and setting the Symbology to display this band as Red is shown below.

Setting Multiple Range Bands

The multiple range band tool () allows you to create a user defined number of equally spaced range bands. Pressing this tool presents the dialog of Figure 39.

The definitions of the values are:

• Start Value – The low value of the first band
• Increment by – The height of each band
• Number of bands – The number of rows you wish to create

The result of creating the 20 bands defined in above is shown below.

Elevation Symbology

The Symbology tool allows you to set symbology functions for the Elevation display. Pressing the Symbology button invokes the Elevation Symbology dialog.

Elevation currently is restricted to a single point size for all elevation ranges being displayed. The Point Size setting on the Symbology dialog is the size that points will be displayed with Legend is selected for the Point Size setting on the main Elevation tab of Live View.

The Symbology dialog controls the display options for both the Gradient and Color Band display modes.

Gradient

The default symbology for elevation gradient (if you have not added color bands that have been set to a solid color) is a color ramp. The most common (and default) symbology is a color ramp from blue for the lowest values of elevation to red for the highest values. The mapping of color to elevation is control by the Gradient Stretch section of the dialog.

There is also a grey scale ramp available on the Symbology dialog. This will map the elevations to a grey scale rendering. The grey scale mapping can be particularly effective when adding distinct color bands to a gradient display.

You can invert either ramp by checking the Invert button. For example, if you invert the grey scale ramp, white will map to the lowest elevation and black to the highest.

Gradient Stretch

The Gradient Stretch section of the Elevation Symbology dialog (Figure 56) determines how elevations are mapped to the selected gradient. The section to the left determines the sampling area:

• Project – use samples from across the entire project. Use this mode when elevation color gradient must remain constant across the project (quantitative analysis).
• View – The gradient ramp is mapped to the current view. Use this mode when aesthetics are most important.

The Min / Max settings determine how the elevation values within the Sampling Area should be mapped to the color ramp:

• Standard Deviations – The sample standard deviation of the sampling area is computed. The range is then computed by multiplying the standard deviation by the user entered multiplier and subtracting, adding to the sample mean. This method prevents outliers from having an undue influence on the mapping and is the preferred method.
• Minimum/Maximum – this is a direct mapping of the entire range of the sampled data

Display by Elevation Colorbands Settings

The lower section of the Elevation Symbology dialog contains the settings that determine the display characteristics when the view display mode is set to Display by Elevation Colorbands.;

The parameter meanings are:

• Vertical Distance Between Colors – this is the height, in Map View elevation units, of each color band
• Number of Colors – The number of colors that will map prior to repeating the cycle. This is hard coded to 5 for Sharp Transitions and 3 for smooth
• Vertical Distance for a Color Cycle – this is the distance between full cycles of the color banding. It is simply the Vertical Distance X Number of Colors

The Band Transition setting determines the transition from one color to the next:

• Sharp Transition – There will be a sharp edge when transitioning from one color to the next. This is useful when simulating contour lines.
• Smooth Transition – The transition between colors is a gradient.

Per Row Symbology

You can select either “ramp” or a solid color on a per row basis for elevation. For example, four elevation bands have been created in the dialog below. Each band is currently set to map to a solid color. You can toggle a band between a solid color and a ramp mapping by single clicking the color box of the row.

Toggling a row is depicted below. In this example, points with elevations between 120 and 125 will be colorized by mapping to the current gradient color ramp whereas the other three defined bands will be colorized according to their mapped solid colors. Elevations outside of the defined bands will not be displayed unless the filter setting is set to “Superimpose” (see next section).

Filter Modes

Elevation filters allow a superimposition mode.  This mode is set via the Filter setting radio button option on the left side of the dialog (see Figure 60). 

The function of these settings is:

• Off – Ignore the filter. This option is useful when you want to see the overall effect of the filter but you do not want to modify any of the row on/off toggles.
• Superimpose – The entire data set (that is not being blocked by some other Live View filter) is mapped to the currently selected Ramp (e.g. grey scale). The defined ranges in the rows are then superimposed over these data. If a row is turned off (unchecked), the points in that row’s range will be mapped to the currently selected ramp. If the row is on, that row’s selected color will be mapping on top of the current elevation display. Obviously a row must be set to a solid color to observe this effect. In the example below (left) , the second row of the table is superimposed over the grey scale ramp display. Notice that setting the elevation ramp to grey scale allows you to enhance the effect of color bands.
• Filter Only – This mode allows only points mapped to rows in the table that are checked to be displayed (again, assuming they are not being blocked by the filters of any other tab of Live View). The display mode will be ramp or color depending on the selection in the Color column. The example below (right) allows only the second row to be displayed (Elevation ranges from 125 to 130 inclusive) and mapped to yellow.

Left - Superimposed, Right - Filter only

Display Order

Points are displayed in the following order:

• • No Filter – Not applicable

  • Superimpose – Points that are not in the table are first displayed. Rows of the table are then displayed from bottom row to top row. For example, if row three and row two both contain ranges from 10 to 20, the color of the row in the upper position (in this example, row 2) will overwrite those of row 3. This is why we do not worry about overlapping ranges when we create multiple range tables.

  • Filter only – The rows are displayed with upper rows overwriting lower rows (assuming ranges overlap)

Edit and Random Color Assignment

Three tools are included for editing rows, deleting rows and assigning random colors.