Interactive Histogram with Photogrammetric Software

There are cases when performing object analysis using photogrammetry based software, the large or extremely small objects are difficult to evaluate. It happens because the objects are often imperceptible. Therefore, histograms are one of the most useful features to showcase the height variation of the object. Different shading of DEM is a must to have feature in software that creates and visualizes DEMs.

Different shading options

Pixprocessing software provides 3 categories of shading:

• Gradient;
• Orthophoto;
• Flat shaded;

Each option is used in different situations.

Gradient shading

Gradient shading allows user to choose from numerous available styles to get the desired outcome. Besides the ability to select the most aesthetically pleasing or regionally most used shading option, user can choose particular one that most accurately fits the theme of the subject (for example, reds scale for sandstone piles or greens for grassy hills).

Provided three- color heat scales allows visually intuitive representation of extremely high elevation differences.

The ability to choose the shading interval helps to control the smoothness and clarity of DEM. For instance, having very small and fine intervals result in a smooth and visual representation (image above).

Having large interval enables user to quickly calculate heights and its differences without even doing any measurements. For example, the image below has 50 meter intervals.

Besides having the ability to choose the gradients in “Pixprocessing” software, user can also choose where to apply the shading in histogram. This means that no matter what is the overall DEM, its height differences and shading can be applied to a small portion of the objects to quickly visualize the smaller ones located in the same DEM. Bellow a small portion of the DEM shaded:

Orthophoto

As the name implies, orthophoto projects the photographic data on the DEM thus showing the most realistic possible 3d model with textures taken from the photographs.

This shading option most accurately represents the real world at the time photographs were taken and enables user to operate fully visually. One can place contour lines according to “reality”. For example, one sees a waterbody and places that contour line around it. Or sees a different rock layer and marks it with a contour line, or starts measuring from that point.

Flat shaded

Flat shaded is a monochrome option with different shades of the same color. This is the best for seeing the DEM most clearly. Small objects become more visible, slope angles more clearer and textures do not distract or confuse in any way.

Summary

With Pixprocessing software one can easily get a better visualization of the object elements in the selected height level. You can variate:

•  Colour ramp pallete;
• Colour change scale;
• Texture options.

The shading option is a crucial feature for dealing with converging objects as it quickly accentuates the surface irregularities. Min and max height value selection of the histogram enables a better visualization of the object elements in the selected height level.