Blender Geometry Nodes Sample Nodes: Data Transfer and Proximity

What will you learn in this tutorial?

Sampling nodes in Geometry Nodes are used to extract data from relationships between geometry and positions. This tutorial focuses on three nodes: Sample Index reads values at specific indices; Geometry Proximity returns the nearest-position and distance information; and Raycast checks whether rays intersect target geometry.

Thinking about these nodes in terms of architectural modeling and visualization makes it easier to choose the right one. For example, relating points on two geometries by their indices, measuring an object’s distance from a surface, and checking for a hit against a target surface in a specific direction are different tasks. These nodes are not interchangeable; choose one based on the data you need.

Requirements and source scope

The sources are Blender manual pages describing the functions of Geometry Nodes. Details about Sample Index, Geometry Proximity, and Raycast come from the manual’s “latest” pages. Another manual page, labeled Blender 5.2 LTS, provides the table of contents for the Sample Geometry Nodes section; its detailed node descriptions have not been used here.

The guide therefore focuses on what these nodes do and on the data relationships to watch for. The sources do not specify a project file, add-on, computational requirements, or pricing. The architectural examples below are use cases created to make the nodes’ functions concrete; the sources do not describe a ready-made façade or interior setup.

Before you start, identify which geometry you’ll read data from, which geometry will use the result, and what output you need. Are you transferring a position or field value, looking for the nearest point, or checking for an intersection in a particular direction? These questions clarify the purpose of your setup.

1. Retrieve values by index with Sample Index

Sample Index retrieves values from source geometry at selected indices. The Geometry input specifies the geometry to read from, the Value input specifies the field to evaluate on that geometry, and the Index input determines which indices to sample. The node’s Value output returns the values retrieved from the source geometry. The data type and the domain on which the sampling is evaluated are also among the node’s properties.

Consider transferring position values from one geometry to another in an architectural model. First, define the field to read from the source geometry and the indices to use for matching the values. This creates an index-based relationship between two geometries, but whether the indices represent the same physical points depends on the structure of the geometries. The Blender manual notes that this method works best when both geometries have the same number of points and the same topology.

So don’t assume that matching shapes mean matching indices. If the point counts or topology differ, a given index may correspond to a different position on each geometry. Connecting different indices to the Index input can change the order of the values; do this only when that is the intended mapping.

Another important detail is how Sample Index evaluates the Point domain. This domain is shared by Mesh, Point Cloud, and Curve components; the node checks the first non-empty component in the order Mesh, Point Cloud, then Curve. If you need to sample a specific component, you can separate the components with the Separate Components node.

When the Geometry input is the same geometry on which the field is evaluated, the manual generally recommends Evaluate at Index instead. Avoiding a geometry socket in this setup can make it easier to reuse and share in other contexts. Before using Sample Index, check whether you really need to retrieve values from a different source geometry.

2. Find the nearest position with Geometry Proximity

Geometry Proximity calculates the nearest position on target geometry. The Geometry input specifies the geometry to search, while Sample Position defines the starting position for finding the nearest point. Its main outputs are Position and Distance: one gives the nearest position on the target, and the other gives the distance between the source position and that point. The Is Valid output reports whether sampling succeeded; the operation may fail when the sampled group is empty.

For example, if you need distance information for points near a surface, specify the target geometry and the positions to measure from. Then plan how the Distance output will be used in the next operation. The Map Range node can help create an effect that falls off over a specified distance; the Blender manual specifically notes this use. Set value ranges according to the geometry and the task at hand.

The Target Element property selects the kind of target element used to calculate proximity. Faces finds the nearest position on the faces of the target mesh, Edges on its edges, and Points on its points or vertices. According to the manual, Points is the fastest mode in most cases and works with both mesh and point cloud geometry. Faces and Edges are available only for mesh geometry. If you need the nearest position on a surface, don’t assume that choosing Points will give the same result.

The node also has Group ID and Sample Group ID inputs. Group ID separates elements of the input geometry into groups; Sample Group ID specifies which group to search for the nearest element in. Keep in mind what these inputs constrain in a grouped setup.

3. Check surface intersections with Raycast

Raycast sends rays from the node’s connected geometry context toward a target mesh. Target Geometry specifies the geometry the rays will test against. Source Position defines the starting point of each ray, Ray Direction its direction, and Ray Length the maximum distance the ray can travel before an intersection is counted. If Source Position isn’t connected, the starting position is evaluated as though a Position node were connected.

When looking for an intersection from a part of a model toward an opposing surface, define the starting position, direction, and length for the task. Is Hit reports whether each ray reached the target. When an intersection occurs, Hit Position gives the intersection position, Hit Normal the surface normal, and Hit Distance the distance between the start and the intersection. If the ray doesn’t hit the target, Hit Distance returns the specified Ray Length value.

If you also need a field value from the target surface at the intersection point, you can use the Attribute input. The field connected to this input is evaluated on the target geometry and transferred to the intersection points, where it is provided through the Attribute output. The Interpolation property determines how target-mesh attributes are transferred to the result: Interpolated smoothly interpolates vertex and vertex-face values, while Nearest selects the value from the nearest vertex.

How can you use these nodes in architectural and archviz workflows?

When working with façade elements, interior components, or scene geometry, first define the relationship you need. Sample Index may be suitable for retrieving values by index between geometries with matching topology and point counts. Use Geometry Proximity when you need a distance to a surface or the nearest position; Raycast is a better fit when you need to reach target geometry in a specific direction and retrieve intersection data.

Before moving on to a production scene, verify the target geometry type and which component the node is working on. In Geometry Proximity, the Target Element selection matters; in Sample Index, so do matching indices and topology; and in Raycast, the starting position, direction, and ray length affect the results. These details are particularly important for modeling teams building reusable geometry setups and archviz artists experimenting with surface-based effects. The manuals provide no information about hardware requirements, licensing terms, or compatibility with other software, so no assumptions should be made about those topics.

Common mistakes

• Not checking point counts and topology when using Sample Index can lead to unexpected index matches.

• Overlooking that the first non-empty component may be used for the Point domain can result in sampling data from the wrong component.

• With Faces or Edges selected in Geometry Proximity, failing to check whether the target is a mesh can lead to incorrect expectations.

• Interpreting the distance without checking the Is Hit result in Raycast can be misleading; if there’s no intersection, Hit Distance returns the ray length.

• Ignoring Is Valid in Geometry Proximity can make it harder to spot an empty sampling group.

Next steps

Start by testing the nodes independently on simple geometry. For Sample Index, begin with geometries that have matching point counts and topology. Compare which targets the Points, Faces, and Edges modes use in Geometry Proximity. In Raycast, observe how the starting position, direction, and length affect the intersection results.

If the result differs from what you expected, don’t look only at the visual output; also review control values such as Is Valid and Is Hit, the selected target component, and the field being used. Moving to more complex scenes before understanding exactly what the node is sampling can make it harder to find the cause of an error.

Sources and license

This tutorial has been adapted into Turkish based on descriptions on the Sample Index, Geometry Proximity, and Raycast pages in the Blender manual; these pages are from the “latest” manual. The Blender 5.2 LTS Manual page was used as the source for the node list in the Sample Geometry Nodes section. The source documents are licensed under CC BY-SA 4.0.