Support
The point cloud looks black or disappears when zooming
Summary
When zooming towards a point cloud it is common for it to disappear partly or completely, to look "like a curtain" or to show black areas even though there are points in them. In most cases this is not a fault, but a matter of where the viewpoint is placed with respect to the cloud and of how point size is represented. This article explains how to restore the view by setting the camera pivot point correctly, when to switch to perspective in order to move through interiors, how to gain sharpness at close range and what to do when there is not enough memory for very large or very dense clouds.
Applies to
TCP PointCloud Editor. The documented cases do not state a specific version number, so it is not restricted to any version.
Navigation and display of point clouds in the 3D viewer.
Symptoms
When zooming towards the cloud, it disappears sometimes but not always, or it is lost completely and cannot be centred again.
When getting closer, the points look "like a curtain" or distorted.
The screen is progressively clipped to black as you zoom in, even though there are points in those areas.
In interiors (tunnels, buildings...) the walls are always in front and the structure cannot be walked through.
When getting close to a low-density cloud, gaps appear between the points and sharpness is lost.
In very large or very dense clouds, the full detail is not loaded when getting closer.
The cloud cannot be told apart from the viewer background, as if nothing had been loaded.
Cause
When the viewpoint (camera pivot point) is inside the cloud or below the points, zooming forward leaves points "behind" the clipping plane, which is why they seem to disappear.
Point size is expressed in pixels: at a distance the points tend to overlap in the same pixel and the cloud looks more solid, whereas getting closer —especially in low-density clouds— reveals the gaps.
The orthographic view is not suitable for moving inside closed structures, because the walls are always in front.
In very large or very dense clouds, the available memory may not be enough to load the full detail at close range.
The cloud may be displayed with a solid colour identical to the background colour of the 3D viewer: it is loaded and in place, but cannot be told apart from the background.
Solution
Case: the cloud disappears or black areas appear when zooming
Perform a zoom extents to frame the whole cloud.
Set the camera pivot point by double-clicking on a point in the area you want to inspect; it is advisable to choose one of the highest points in that area. That point becomes the camera target.
Zoom in with the mouse wheel or by holding down the right button and moving it forwards or backwards, always with respect to that point. By centring the view first and keeping the cloud in front of you, it is no longer lost as you get closer.
Case: in interiors (tunnels, buildings...) the walls block the view
The orthographic view is not suitable for moving inside, because the walls are always in front. Switch to perspective to move within closed structures.
Case: the cloud looks gappy or not sharp when getting closer
Since point size is on a pixel scale, seeing gaps when getting close to a low-density cloud is normal. Increase the point size to gain sharpness at close range.
Case: the cloud cannot be told apart from the viewer background
If the cloud is displayed with a solid colour identical to the background colour, it is not visible even though it is loaded. Change the point cloud colour or its display mode, or else change the 3D viewer background colour in the application settings.
Case: not enough memory for very large or dense clouds
If there is not enough memory to load the full detail when getting closer, select the area of interest first and filter it so that fewer points remain. Working on that subset shows much more detail.
If the problem persists
If after setting the pivot point you still cannot centre the cloud or you see no point to zoom towards, it may be because there are drawing entities at coordinates far away from the cloud. Check the coordinates of the entities in the project.
For cases that these steps do not solve, contact Aplitop technical support through the support chat so that a remote connection can be made and the project analysed.
Category: Point cloud display and editing · Level: Intermediate