This document provides instructions for creating a BLN file from an ESRI Shapefile (SHP) to use for blanking in Golden Software Surfer. It discusses using online converters, editing the BLN file directly in Notepad, and using ogr2ogr and KML as intermediate formats. It also describes using ogrinfo to get extent information and drawing the BLN manually in Surfer if other methods fail. The key steps are converting the SHP to KML, editing the KML file to extract just the coordinates, formatting it as a BLN file, and adjusting the BLN rectangle to match the shapefile extent.

1. How to Create a BLN
file from SHP
Muhammad Jazman
jazman@uin-suska.ac.id

2. Golden Software Surfer
• Create
• base map
• contour
• post and classed post
• Images
• shaded relief
• viewshed
• 3D wireframe
• 3D surface
• Calculate
• length
• area
• profile
• volume

3. Base Map
• Surfer support ESRI Shapefile SHP as your
basemap

4. Base Map (cont.)
• Base Map is better
suited as an overlay
base layer for your
contour

5. Base Map + Contour

7. Problems
• Blanking Grid
• Original Grid is Equally spaced area
• No “BLANK” Shape

8. Original Grid

9. Golden Software Blanking
BLN
• BLN file is used to blank grid
• convert area outside specified BLN file to “BLANK
value”,
Surfer Training Guide - by Tom Bresnahan and Kari
Dickenson page 18

10. But, how to create a BLN from
SHP?
• Do it online
• Golden Software online converter
• failed me almost every time

11. BLN formats
• It’s just a simple ASCII file, you can edit it with
notepad in Windows!
• First Line is number of rows (vertex) and
comma and 0 or 1
• 0 if you blank area outside polygon
• 1 if you blank area inside polygon
• The rest is x and y coordinates

12. notepad
number of rows
0 or 1
x, y coordinates

13. ogr2ogr
• open source tool to convert between various
vector format file in GIS
• Support almost every format in GIS
• but not Golden Software BLN
• ogr2ogr --long-usage
PCIDSK netCDF PDF DB2ODBC ESRI
Shapefile MapInfo File S57 DGN Memory
BNA CSV GML GPX LIBKML KML
GeoJSON Interlis 1 Interlis 2 OGR_GMT
GPKG SQLite ODBC WAsP
MSSQLSpatial PostgreSQL MySQL DXF
Geoconcept GeoRSS GPSTrackMaker
PGDUMP GPSBabel GFT CouchDB
Cloudant ODS XLSX ElasticSearch Carto
AmigoCloud Selafin JML VDV TIGER

14. KML
• KeyHole Markup Language store x and y
coordinates in plain text
• ogr2ogr -f KML out.kml myoriginal.shp
• now, open your out.kml with your text editor,
preferable is Notepad++
• clean all areas but coordinates , before and after

16. replace space with n
• convert space character into newline
• use extended search mode in Notepad++
space
extended

17. Count the Coordinates
• Ctrl + End

18. Add a new line on top of file
• number of coordinates, 0

19. original grid

20. Blank

21. 0 blank outside

22. 1 blank inside

23. Q/A
Mobile: +62 812 1012 7812
Email: kampar@gmail.com <primary>
Email: jazman@uin-suska.ac.id <office>

24. The hard way
Draw your own BLN

25. Draw your blank
• Create a new Plot Document in Surfer
• Import your shp
• DON’T thick / check convert to curve (Polyline)
• Export it again as BLN

27. The hardest part
• Change BLN rectangle to suit your SHP
extents
• How to know your shape extent?
• ogrinfo
• QGIS layer properties

28. ogrinfo
• ogrinfo yourshape.shp
ogrinfo 1473_dumai.shp
INFO: Open of '1473_dumai.shp'
using driver 'ESRI Shapefile' successful.
1: 1473_dumai (Polygon)
file name
layer name

29. ogrinfo yourshape.shp layer
• whilst you know your layer name, ogrinfo it
again
• ogrinfo -geom=NO filename.shp layer
ogrinfo -geom=NO 1473_dumai.shp 1473_dumai
INFO: Open of '1473_dumai.shp'
using driver 'ESRI Shapefile' successful.
Layer name: 1473_dumai
Metadata:
DBF_DATE_LAST_UPDATE=2017-11-05
Geometry: Polygon
Feature Count: 1
Extent: (101.009292, 1.431062) - (101.728169, 2.275318)

30. ogrinfo
• skip –geom=NO to see all coordinates in
specified layer

31. QGIS
• Open your SHP in QGIS
• Double-click to open Layer Property
• Navigate into Metadata
• Scroll down to extent (provided here is Batas,
extent in Bahasa/Indonesian)

32. Now go back to Export
• Change BLN Rectangle using provided extent

33. the results are almost identical
• from KML
• drawing

35. Muhammad Jazman, S.Kom.,MInfoSys
• Serjana Komputer (S.Kom) / Bachelor of Science
in Computer from Universitas Indonesia (2007)
• Lecturer in Politeknik Kampar, a regency owned
polytechnic in Kampar regency (district), Riau
province, Indonesia (2007-2015)
• Master of Information Systems (MInfoSys) from
University of Wollongong, NSW, Australia (2010)
• Civil Servant (2015), serve as lecturer in GIS in
faculty of sciences and technologies, Universitas
Islam Negeri / UIN (state-owned Islamic university)
Sultan Syarif Kasim Riau