openstreetmap / openstreetmap/mod_tile

getting blank tile while using mod_tile with mapnik to serve geotiff file

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Description

Hi, I stuck in one issue where i have geotiff files and i want to use mod_tile but problem is after trying everything i am still getting balnk tile in api response but i tride to generate same tile using python and mapnik i am able to do so.

i am adding all information here

  1. mapnik.xml
<?xml version="1.0" encoding="utf-8"?>
<Map srs="+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs">
<Style name="raster-style">
<Rule>
        <RasterSymbolizer opacity="1.0" scaling="bilinear">
                <Colorizer type="linear" epsilon="0.01">
                        <stop color="black" value="0"/>
                        <stop color="white" value="255"/>
                 </Colorizer>
        </RasterSymbolizer>
</Rule>
</Style>
    <Layer name="GeoTIFF" status="true" srs="+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs">
        <StyleName>raster-style</StyleName>
        <Datasource>
            <Parameter name="type">gdal</Parameter>
            <Parameter name="file">/usr/share/renderd/mod_tile_poc/AQ.tif</Parameter>
            <Parameter name="estimate_extent">true</Parameter>
            <Parameter name="log">/usr/share/renderd/mod_tile_poc/mapnik.log</Parameter>
            <Parameter name="debug">debug</Parameter>
        </Datasource>
    </Layer>
</Map>
  1. /etc/renderd.conf
[renderd]
pid_file=/run/renderd/renderd.pid
socketname=/run/renderd/renderd.sock
stats_file=/run/renderd/renderd.stats
tile_dir=/var/cache/renderd/tiles

[mapnik]
font_dir=/usr/share/fonts
font_dir_recurse=0
plugins_dir=/usr/lib/mapnik/3.0/input

[default]
URI=/osm_tiles/
TILEDIR=/var/lib/mod_tile
XML=/usr/share/renderd/example-map/mapnik.xml
HOST=0.0.0.0
TILESIZE=256

[example-map]
URI=/tiles/renderd-example
XML=/usr/share/renderd/example-map/mapnik.xml

[example-map-jpg]
TYPE=jpg image/jpeg jpeg
URI=/tiles/renderd-example-jpg
XML=/usr/share/renderd/example-map/mapnik.xml

[example-map-png256]
TYPE=png image/png png256
URI=/tiles/renderd-example-png256
XML=/usr/share/renderd/example-map/mapnik.xml

[example-map-png32]
TYPE=png image/png png32
URI=/tiles/renderd-example-png32
XML=/usr/share/renderd/example-map/mapnik.xml

[example-map-webp]
TYPE=webp image/webp webp
URI=/tiles/renderd-example-webp
XML=/usr/share/renderd/example-map/mapnik.xml
  1. this is info about geotiff file
Driver: GTiff/GeoTIFF
Files: AQ.tiff
Size is 7220, 2810
Coordinate System is:
GEOGCRS["WGS 84",
    DATUM["World Geodetic System 1984",
        ELLIPSOID["WGS 84",6378137,298.257223563,
            LENGTHUNIT["metre",1]]],
    PRIMEM["Greenwich",0,
        ANGLEUNIT["degree",0.0174532925199433]],
    CS[ellipsoidal,2],
        AXIS["geodetic latitude (Lat)",north,
            ORDER[1],
            ANGLEUNIT["degree",0.0174532925199433]],
        AXIS["geodetic longitude (Lon)",east,
            ORDER[2],
            ANGLEUNIT["degree",0.0174532925199433]],
    ID["EPSG",4326]]
Data axis to CRS axis mapping: 2,1
Origin = (-180.500000000000000,84.099607528087063)
Pixel Size = (0.050000000000000,-0.050000000000000)
Metadata:
  AREA_OR_POINT=Area
Image Structure Metadata:
  INTERLEAVE=BAND
Corner Coordinates:
Upper Left  (-180.5000000,  84.0996075) (180d30' 0.00"W, 84d 5'58.59"N)
Lower Left  (-180.5000000, -56.4003925) (180d30' 0.00"W, 56d24' 1.41"S)
Upper Right ( 180.5000000,  84.0996075) (180d30' 0.00"E, 84d 5'58.59"N)
Lower Right ( 180.5000000, -56.4003925) (180d30' 0.00"E, 56d24' 1.41"S)
Center      (   0.0000000,  13.8496075) (  0d 0' 0.01"E, 13d50'58.59"N)
Band 1 Block=7220x1 Type=Int32, ColorInterp=Gray
  NoData Value=-255

Contributor guide

No contributing guide indexed for this repository

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the supplied mapnik.xml and /etc/renderd.conf, then inspect the renderd and mapnik.log paths while reproducing the blank tile response. Compare that behavior with the Python-generated tile and the GeoTIFF metadata shown in the issue; done means the configured tile endpoint returns a rendered tile rather than a blank response.

Written by the indexing model from the issue text.

Assessment

Tech stack
apache, python
Domain
backend
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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