Houdini 20.0 Reference Stand-alone utilities


Reduces polygons in a file.

greduce reduces the polygon count of an object while trying to keep the general shape of the object. greduce can also be run in batch mode, where no graphical interface appears and the conversion is performed from the command line only.

The Open Triangulated and Open 4 sided File menu options allows you to open the geometry with triangles or quadrilaterals as the polygon type respectively.


It is recommended that you use the percent reduction buttons for speedier operations with this tool. Files with many polygons may take a long time to reduce using the reduction factor and angle parameters.

greduce <<filename>>
greduce teapot.bgeo

This will start the tools interactive mode, where you can reduce the object’s polygon count using the sliders and controls provided.

There are two controls for determining the polygon reduction. These are represented as sliders at the bottom of the window. The reduction factor is the primary control. However, this should be used in conjunction with a small increase in the angle factor (e.g. 5).

To simply remove planar polygons, set the reduction factor to a small number and the angle factor to a small number (i.e. 0.001, 0.001). Beneath the sliders are a set of buttons which can be used to reduce the polygon count by differing degrees. For example, remove 10% of the polygons. These controls are approximate and are usually good to plus or minus 5%. In some cases, it will not be possible for the program to remove a large number of polygons. In these cases, hitting 90% reduction will result in a smaller percentage actually removed.

greduce [-v] [-t|-q] -r reduction_factor -a angle infile outfile 

This reduces the geometry using the reduction factor and angle factor specified.

greduce [-v] [-t|-q] -p percentage [-a angle] infile outfile 

This reduces the polygon count by the percentage specified. The angle does not have to be specified, though it can make a small difference in the resulting geometry.

greduce -v -p 40 -a 10 teapot.bgeo reduced.bgeo 

This example will run the polygon reduction program in “batch” mode. With the -v specified, the resulting statistics will be displayed. Sample output from the above command might look like:

Used reduce = 0.151 and angle = 10 Reduced to 170 polygons. 40.9722% reduction 
greduce -v -r 0.08 -a 10 teapot.bgeo reduced.bgeo 

The above command will reduce the polygons in the teapot file using the parameters specified. Again, the verbose option (-v) will cause some statistics to be displayed when the program is finished. This output will look something like:

Reduced to 193 polygons. 32.9861 % reduction 



Verbose option for batch mode versions


Triangulate or make quadrilaterals out of the input file


Reduction factor (corresponds to upper slider in interactive version)


Angle of reduction (corresponds to lower slider in interactive version)


The amount, expressed as a percentage, of the original geometry to reduce.

Stand-alone utilities

  • abcconvert

    Convert between Alembic formats.

  • abcecho

    Print information about an Alembic file.

  • abcinfo

    Print information about an Alembic file.

  • chchan

    Copies channel collection to/from action channel format.

  • chcp

    Copies channel collection file to another format.

  • chinfo

    Prints information about a channel collection file.

  • claudio

    Copies CHOP data (clip) to/from audio formats.

  • clchan

    Copies CHOP data (clip) to/from action channel format.

  • clchn

    Copies CHOP data (clip) to/from channel collection format.

  • clcp

    Copies CHOP data (clip) to another format.

  • clinfo

    Prints information about a CHOP data (clip) file.

  • dsmconvert

  • dsmmerge

  • dsparse

    Parses and displays dialog scripts.

  • gabc

    Convert between Alembic and Houdini geometry.

  • gconvert

    Convert between Houdini polygon formats.

  • gdxf

    Converts DXF polygons to/from Houdini format.

  • geodiff

    Display Geometry Differences.

  • geps

    Converts EPS files to Houdini polygon format.

  • giges

  • ginfo

    Prints polygon file statistics.

  • glightwave

    Converts LightWave files to/from Houdini format.

  • gpdb

    Converts .pdb files to/from Houdini format.

  • gplay

    Geometry viewer.

  • gply

    Converts .ply files to/from Houdini format.

  • gptex

    Makes a ptexture image file from a geometry file.

  • greduce

    Reduces polygons in a file.

  • gwavefront

    Converts .obj files to/from Houdini format.

  • hcollapse

    Collapses a directory structure.

  • hcpio

  • hexpand

    Expands hip files into a directory structure.

  • hkey / License Administrator

    Opens a graphical user interface for viewing and managing licenses and license server options.

  • hoiiotool

    Swiss-army knife of image operation tools.

  • hotl utility

    Command line utility to work with .hda/.otl files.

  • hrender

  • hsc

  • hscript

    Command line HScript interpreter.

  • hserver

    Houdini communicates through this proxy server to the sesinetd licensing daemon.

  • htexcache

    Query or modify the disk texture cache.

  • husk

    Command line utility for rendering a USD file using Karma or some other Hydra client.

  • i3dconvert

  • iautocrop

    Crops images based on pixel values.

  • icineon

    Convert images from 10-bit Cineon format to an 8 bit format.

  • icomposite

  • iconvert

    Converts an image of one type to another type.

  • icp

    Isolate a region of an image in a new image.

  • idenoise

    Removes noise from an image file.

  • idiff

    Display Image Differences.

  • iflip - Flip Image

  • iinfo

    Outputs information about an image.

  • ilut

    Generates a lookup table (LUT) from standard channel formats or another LUT.

  • ilutcomp

    Generates a single lookup table (LUT) from from two LUTs.

  • ilutinfo

    Prints information about a lookup table (LUT) file.

  • imaketx

    Creates mipmapped .exr or .rat textures from image files.

  • imdisplay

    Sends an image to an mdisplay window.

  • iprint

    Prints the RGBA values for an image as text.

  • iquantize

    Reduces the number of colors in an image.

  • isixpack

    Generates an environment/reflection map from six images representing the six sides of a cube, or a cross image.

  • itilestitch

    Assemble a series of image files with crop windows into a single image.

  • izg

    Converts Z-depth images to 8-bit grayscale images.

  • Launcher

    The Houdini Launcher downloads, installs, upgrades, and uninstall Houdini and its components.

  • mcacclaim

    Converts an Acclaim motion file to a Houdini script and channel file(s).

  • mcbiovision

    Converts a BioVision motion file to a Houdini script and channel file(s).

  • mcmotanal

    Converts a Motion Analysis TRC motion file to a Houdini script and channel file(s).

  • mcp

    Convert an image sequence to a movie file.

  • minfo

    Prints information about movie files.

  • mqserver

    Message Queue Server for PDG/TOPs

  • py23convert

    Convert Python 2 expressions in HDAs to Python 2/3.

  • renderstatsoverlay

    Generates a (possibly scaled down) version of a rendered image with render statistics baked in.

  • renderstatsreport

    Generates an HTML page containing render statistics from an EXR image.

  • sesictrl

    Sets Houdini license server options from the command line.

  • sesinetd

    The Houdini license server. This program runs in the background managing Houdini licenses.

  • siminfo

    Prints simulation cache file statistics.

  • spiff

    Display Text Differences.

  • spy

    Shell utility for navigating the UNIX filesystem.

  • usdview

    Command line utility for viewing and inspecting USD scenes.

  • vexcache

    Query or modify the VEX compile cache.

  • vexexec

    Execute a cvex shader.