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Questions tagged [compression]

The encoding of digital information in order to store it using fewer bits.

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29 views

Different methods to reduce georeferenced Imagery size

I have geo-referenced imagery with a size of around 7GB. When I apply GDAL Leaflet compression on the imagery, the size is reduced to 400MB. I have to generate tiles from this geo-referenced imagery. ...
4
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2answers
348 views

Why did Esri create .zlas compressed LiDAR files instead of adopting .laz?

I am talking about the Esri Optimized LAS file format for compressed LiDAR files (.zlas). While the uncompressed format (.las) from ASPRS was adopted by practically the entire Remote Sensing and GIS ...
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0answers
44 views

Adding compression variable to CopyRaster_management for TIFF Raster Dataset?

I am using ArcGIS Desktop 10.1. I need tiff orthos to have NO compression. I'm using a python script to parse through directories and add 4-band data to the images. It works great ... but the ...
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0answers
51 views

Compress GPX file

I have a .gpx file with a size of about 20MB. I want to load this file into a bicycle navigation application but somehow the file seems to be tool large. Are there ways to compress the file? In QGIS ...
2
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1answer
30 views

State ID Count after SDE Compression

I have a Enterprise Geodatabase (SDE) in SQL Server 2016. I have a nightly python script to preform some maintenance including the compress function (among other things). I am noticing that the ...
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1answer
146 views

JPEG compressed Geotiff files convert to JPEG without loss

I am new to GIS application and had just started working with Geotiff files. Background: Currently, I am provided with big Geotiff files around 200 MB - 500 MB each as raw data from my vendors. Are ...
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3answers
2k views

Is raster lossy and vector not lossy?

I am new to GIS, in school for it actually, but I come from a photography / graphic design background. So that said, I always thought that vector graphics were not lossy (scale up or down, doesn't ...
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0answers
52 views

compress error arcgis multiuser database postgis backend

arcgis 10.5.1, postgresql 9.5 using PG_Geometry backend. this database is working fine but I have some spatial tables(most are views..not sure why) that do not have an SRID as seen below when I try ...
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1answer
139 views

How to enable LZW compression in a QGIS python code?

I have this simple code that batch sieves all the raster in a given directory. I found outthat the resulting output files (241MB )are pretty much larger than the input(~31MB). In ArcGIS, there is a ...
4
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0answers
146 views

Is it possible to get the compression level of a GeoTiff?

When creating a GeoTiff and using Deflate or LZW as compression it is possible to select the level of compression from 1 to 9. Is it possible afterwards to see which level was used? I have a lot of ...
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1answer
269 views

Mapbox GL JS compressed GeoJson files?

I am currently using Mapbox GL JS and pull multiple GeoJson files from the style.json file. Each file in about 10MB and takes too long to load. Is there a way to compress the files and uncompressed ...
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1answer
197 views

Sending compressed folder with shapefiles and QGIS? [duplicate]

When I compress my QGIS file with the folder containing all my shapefiles, how can I maintain the paths? For example, I made a map on QGIS using a large amount of shapefiles. Once done, I save my ...
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1answer
343 views

How to apply compression (e.g. LZW) when exporting a map from QGIS composer to TIF?

QGIS > Composer > Export as image > *.TIF I need to apply lossless compression (e.g. LZW or ZIP), when exporting a map from QGIS (v2.18) composer to TIF image. This settings are missing in the export ...
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1answer
98 views

Identifying Compression Ratio in a ECW raster file

I'm trying to identify and verify the compression ratio of an ecw raster file and I cannot find the information under properties > source tab. I'm trying to using ArcMap 10.5 to do so.
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0answers
99 views

(ArcMap) ECW to LZW-compressed TIF - why does the filesize pentuple?

I have a few ECW tiles that I want to combine and save as 8 bit unsigned TIF. Together, they're about 180 MB. When I use mosaic to new raster, the resulting TIF ends up being a whopping 1.8GB big. Is ...
3
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1answer
105 views

Compressing raster using PyQGIS?

I have the following code which batch saves rasters in qgis using the python terminal: myDir = 'd:/output/' layers = iface.legendInterface().layers() pipe = QgsRasterPipe() for layer in layers: ...
5
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2answers
3k views

Cropping a large geotiff in QGIS

I have a DEM of Saint Lucia, obtained from the CHARIM database. It is a large geotiff (150MB), and I would like to crop it as I only need a small part of it. I have been trying to use Raster -> ...
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1answer
583 views

QField and compressed raster formats

In our project we need to use rasters offline on QField. Our tablets are a very limited software and using uncompressed rasters is too slow to be practical. First, we try to convert our tif files to ...
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1answer
114 views

GDB Compression Not Updating Base Tables

I'm having an issue when compressing a database the edits are not being posted to the base table immediately, this sometimes takes hours until I can see the edits. Right now the only way I can force ...
3
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1answer
114 views

Reducing the accuracy of coordinate data

Let's say that I have a large set of latitude, longitude pairs which are accurate to 5 meters. I want to reduce their accuracy to 100 meters so that they render quicker and consume less storage space. ...
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2answers
440 views

Problem with rendering jpeg compressed image - Caused by: java.lang.ClassNotFoundException: org.libjpegturbo.turbojpeg.TJException

I have a problem with rendering GeoTiff image that is jpeg compressed image. It's size is about 50MB but uncompressed it is 1200MB. This is what gdalinfo command tells about compressed image: ...
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1answer
893 views

Zipping up a shapefile [closed]

I know this may be a topic for Stack Overflow, but it might be worth answering here as it related to shapefiles. I am trying to zip up a shapefile. I have selected all the components of the shapefile ...
2
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1answer
141 views

Compress Raster in ArcMap without generating a new File

I have several uncompressed rasters (FGDBR format) stored in a File-GDB. Now I want to compress this data. The only way I know is to use the "Copy Raster" tool but this will generate a new raster with ...
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0answers
194 views

4 Band JPEG2000 compression for RGBNIR

The South African National Mapping Agency acquires multispectral imagery (R,G,B and NIR)and currently compresses its aerial imagery with JPEG compression with a TIF wrapper. So we give out JPEG (Q3) ...
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0answers
72 views

ArcGIS Raster Shows No Compression

I am using ArcGIS 10.2 to add raster layers to a geodatabase. When I create a new 32-bit floating-point raster layer, I specify that it should use "Packbits". After the layer is created, I check ...
3
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1answer
258 views

Compress Raster Overviews

I have a large number of Raster Aerial images which I have been building VRT files for. I'm also building overview for them with the following code gdaladdo -r average -ro Y:/vrt/sussex_2016_aerial....
3
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0answers
88 views

Reading Jp2 compression level using ArcPy? [closed]

Is the compression quality level used to create a JPEG2000 image stored somewhere inside the file, and how to read it? I would like to know if my images where generated using a lossless compression ...
4
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2answers
64 views

How to find fluctuant parts in a trajectory

I am currently doing an assignment on how to compress a trajectory. Given a trajectory T1 in figure 1, and I want to get a compressed version as T2. For segments p0~p3 and p6~p9 in T2, I can obtain ...
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1answer
145 views

How do I keep my python loop going if there is an error with an SDE workspace?

I have a folder with several .SDE connections. I want my Python code to execute various SDE maintenance procedures (such as compress) on each of these databases. If there is a bad/corrupt/not ...
2
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0answers
70 views

Knowing byte address and byte length of “strip” in LZW-compressed GeoTiff with vanilla PHP?

I have a situation where I need to read cell values from a GeoTiff using vanilla PHP, and while I've been successful reading values from an uncompressed TIF (~800MB), I'm having difficulty reading ...
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1answer
171 views

How to configure Apache for topojson gzip files [closed]

Building an online interactive map with leaflet and some heavy layers with my spatial data in topojson format. I have been reading about gzip but I am still uncertain how to configure it. Do I need ...
2
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1answer
357 views

How to remove compression from jpeg2000 NAIP imagery?

I downloaded a 4-band 1m spatial resolution NAIP image from Earth Explorer. The default image format is jpeg2000. You can see the trees in the attached image appear grainy, more so than what you ...
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1answer
3k views

Extract multiple tar.gz files [closed]

I'm new here and in the world of Python scripting mostly with the arcpy module. I hope you can help me with the trouble that I have. I'm trying to develop a script to extract or uncompress multiple ...
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0answers
170 views

TileStache PNG Optimization

A Tilestache config file has a "png options" object that passes its config straight through to the Python Imaging Library (PIL). Setting optimize: true does some kind of optimization as the file is ...
2
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0answers
556 views

Compression Algorithms output files larger than the originals. Why? [closed]

I'm currently attempting to write a script that will compress a few hundred .tif files. I've tried two approaches, first I wrote a script in Python using CopyRaster_management() function and the ...
1
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1answer
696 views

Python Script to batch compress .tif files using LZW compression

I am currently trying to batch compress a folder of .tif files using LZW compression in order to free up storage space. I've been using this script in ArcMap's python window, adapted from here: # ...
1
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1answer
1k views

How to unzip multiple folders with FME 2014

I have downloaded 21 zipped folders using the HttpFetcher transformer and I cannot figure out how to get FME to unzip these files. I've seen some posts about using either the TclCaller or ...
3
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3answers
193 views

Bad SRTM files?

I have noticed that between 1-3% of SRTM .hgt files downloaded for a continent when un-zipped are of TGA image, font image or text format and do not contain elevation data. Results are the same ...
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0answers
55 views

Has anyone success using subset an image such as NAIP?

Has anyone any luck subsetting a small part out from NAIP? I'd like to hear your feedback on pros or cons on how to subset an image from NAIP despite they are in mrsid and their uncompressed file size ...
3
votes
1answer
2k views

Save map in raster format from QGIS using compression

Is there a method to save a map in raster format from QGIS using compression? For exemple from "Export map" in ArcGIS there are many options to compress the images depending on the file type (tiff, ...
10
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5answers
3k views

Raster diff: how to check if images have identical values?

Is there a means to check to see if any 2 given raster layers have identical content? We have a problem on our corporate shared storage volume: it's now so big that it takes over 3 days to conduct a ...
1
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1answer
112 views

Compressing multiple static layers to single layer to make web map loading faster?

In our web application there are many layers to be loaded, this cause the loading of map very slow. I am seeking a way to compress multiple static layers to a single layer to make the loading faster....
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3answers
5k views

What methods exist for geohash of polygon?

GeoHash is an excellent method to code the latitude and longitude of a point into a string. It's concise, due to the use of numbers + letters, and the precision can be tuned adding characters at the ...
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1answer
1k views

ERDAS Imagine ecw compression settings

We have some jp2 or img satellite images that we compress to .ecw using ERDAS Imagine. We have realized that with some images we are losing too much information while doing that. What i wanted to ask ...
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0answers
393 views

Raster format similar to ECW

I need an alternative to the ECW format that we currently have for a new series of Ordnance Survey maps. The ECW format looks clearer and less pixelated than the new maps in Tif format (in QGIS). ...
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0answers
2k views

Why does compressed & zipped/unzipped file geodatabase give Open Failed Error opening feature class Cannot access secured data?

In ArcGIS 10.2 for Desktop, a colleague compressed a file geodatabase and then zipped it and sent it to me via email. I unzipped it and was unable to add any of the feature classes into my map ...
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1answer
1k views

When trying to convert an .e00 file into a shapefile with ogr2ogr, getting “ERROR 4: This looks like a compressed E00 file”

When I ran this command: ogr2ogr topo.shp flowe86hyp.e00 I got this error: ERROR 4: This looks like a compressed E00 file and cannot be processed directly. You may need to uncompress it first ...
4
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1answer
797 views

What does the predictor switch do while compressing geoTIFFs in GDAL

I am merging several geoTIFFs into one and am using the -co COMPRESS=DEFLATE create option for geoTIFFs. An additional switch is the predictor switch. What does it do? The GDAL website is not clear ...
2
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2answers
5k views

How to compress raster image for publishing?

I have a (8-bit) satellite image that is e 6 gb. Is there a way I can compress the image smaller size without losing the quality? Format: .tif Reason: After publish the image, I notice a higher usage ...
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2answers
2k views

How can I reduce the size of my file geodatadase?

We're using file geodatabase for tax mapping. we save building photos and there are 6000 buildings. The size of this data 2GB. So loading the data takes a lot of time we are not unable to do work ...