diff --git a/tests/test_data/gcp_list.txt b/tests/test_data/gcp_list.txt
index 3825eacf..bc70e419 100755
--- a/tests/test_data/gcp_list.txt
+++ b/tests/test_data/gcp_list.txt
@@ -1,19 +1,31 @@
 EPSG:32617
-274914.738	4603349.014	400	1229.676	514.215	DJI_0068.JPG	HV01
-274914.738	4603349.014	400	1268.023	31.309	DJI_0104.JPG	HV01
-274914.738	4603349.014	400	1350.499	1506.619	1JI_0076.JPG	HV01
-274915.887	4603307.715	400	1276.695	1043.561	DJI_0068.JPG	HV02
-274915.887	4603307.715	400	750.239	81.604	DJI_0104.JPG	HV02
-274915.887	4603307.715	400	336.897	634.845	DJI_0083.JPG	HV02
-274915.887	4603307.715	400	1344.332	956.654	1JI_0076.JPG	HV02
-274985.284	4603319.756	400	2125.152	841.227	DJI_0068.JPG	HV03
-274985.284	4603319.756	400	919.044	903.661	DJI_0104.JPG	HV03
-274985.284	4603319.756	400	483.157	1088.268	1JI_0076.JPG	HV03
-274920.710	4603258.802	400	1376.513	1662.513	DJI_0068.JPG	HV04
-274920.710	4603258.802	400	183.508	181.808	DJI_0104.JPG	HV04
-274920.710	4603258.802	400	919.236	537.724	DJI_0083.JPG	HV04
-274920.710	4603258.802	400	2202.425	1319.122	DJI_0063.JPG	HV04
-274920.710	4603258.802	400	604.750	771.373	DJI_0074.JPG	HV04
-274879.571	4603204.279	400	1617.581	1008.779	DJI_0083.JPG	HV05
-274879.571	4603204.279	400	1505.237	849.416	DJI_0063.JPG	HV05
-274879.571	4603204.279	400	1291.725	1257.747	DJI_0074.JPG	HV05
+## comment: the first line must contain EPSG. ( mandatory )
+## x1 y1 z1 pixelx1 pixely1 imagename1 idGCP
+## 0/0 of Pixel Coord = Upper left corner pixelX(column_0..) pixelY(row_0..)
+# order by GCP
+# GCP01
+274914.738    4603349.014    400    1229.676   514.215    DJI_0068.JPG    HV01
+274914.738    4603349.014    400    1268.023    31.309    DJI_0104.JPG    HV01
+#274914.738   4603349.014    400    1350.499 -1506.619    1JI_0076.JPG badHV01
+274914.738    4603349.014    400    1350.499  1506.619    1JI_0076.JPG    HV01
+# this is a comment. skip this and empty lines
+
+# GCP02
+274915.887    4603307.715    400    1276.695  1043.561    DJI_0068.JPG    HV02
+274915.887    4603307.715    400     750.239    81.604    DJI_0104.JPG    HV02
+274915.887    4603307.715    400     336.897   634.845    DJI_0083.JPG    HV02
+274915.887    4603307.715    400    1344.332   956.654    1JI_0076.JPG    HV02
+# GCP03
+274985.284    4603319.756    400    2125.152   841.227    DJI_0068.JPG    HV03
+274985.284    4603319.756    400     919.044   903.661    DJI_0104.JPG    HV03
+274985.284    4603319.756    400     483.157  1088.268    1JI_0076.JPG    HV03
+# GCP04
+274920.710    4603258.802    400   1376.513   1662.513    DJI_0068.JPG    HV04
+274920.710    4603258.802    400    183.508    181.808    DJI_0104.JPG    HV04
+274920.710    4603258.802    400    919.236    537.724    DJI_0083.JPG    HV04
+274920.710    4603258.802    400   2202.425   1319.122    DJI_0063.JPG    HV04
+274920.710    4603258.802    400    604.750    771.373    DJI_0074.JPG    HV04
+# GCP05
+274879.571    4603204.279    400   1617.581   1008.779    DJI_0083.JPG    HV05
+274879.571    4603204.279    400   1505.237    849.416    DJI_0063.JPG    HV05
+274879.571    4603204.279    400   1291.725   1257.747    DJI_0074.JPG    HV05
diff --git a/tests/test_data/gcp_list_by_photo.txt b/tests/test_data/gcp_list_by_photo.txt
new file mode 100644
index 00000000..1f4a702d
--- /dev/null
+++ b/tests/test_data/gcp_list_by_photo.txt
@@ -0,0 +1,32 @@
+EPSG:32617
+## comment: the first line must contain EPSG. ( mandatory )
+## x1 y1 z1 pixelx1 pixely1 imagename1 idGCP
+## 0/0 of Pixel Coord = Upper left corner pixelX(column_0..) pixelY(row_0..)
+# this is a comment. skip this and empty lines
+
+# order by photo
+274920.710    4603258.802    400   2202.425   1319.122    DJI_0063.JPG    HV04
+274879.571    4603204.279    400   1505.237    849.416    DJI_0063.JPG    HV05
+#
+274914.738    4603349.014    400    1229.676   514.215    DJI_0068.JPG    HV01
+274915.887    4603307.715    400    1276.695  1043.561    DJI_0068.JPG    HV02
+274920.710    4603258.802    400   1376.513   1662.513    DJI_0068.JPG    HV04
+274985.284    4603319.756    400    2125.152   841.227    DJI_0068.JPG    HV03
+#
+274920.710    4603258.802    400    604.750    771.373    DJI_0074.JPG    HV04
+274879.571    4603204.279    400   1291.725   1257.747    DJI_0074.JPG    HV05
+#
+#274914.738   4603349.014    400    1350.499 -1506.619    1JI_0076.JPG badHV01
+274914.738    4603349.014    400    1350.499  1506.619    1JI_0076.JPG    HV01
+274915.887    4603307.715    400    1344.332   956.654    1JI_0076.JPG    HV02
+274985.284    4603319.756    400     483.157  1088.268    1JI_0076.JPG    HV03
+#
+274915.887    4603307.715    400     336.897   634.845    DJI_0083.JPG    HV02
+274920.710    4603258.802    400    919.236    537.724    DJI_0083.JPG    HV04
+274879.571    4603204.279    400   1617.581   1008.779    DJI_0083.JPG    HV05
+#
+274914.738    4603349.014    400    1268.023    31.309    DJI_0104.JPG    HV01
+274915.887    4603307.715    400     750.239    81.604    DJI_0104.JPG    HV02
+274985.284    4603319.756    400     919.044   903.661    DJI_0104.JPG    HV03
+274920.710    4603258.802    400    183.508    181.808    DJI_0104.JPG    HV04
+
diff --git a/tests/test_data/idgcp_QGIS_label.png b/tests/test_data/idgcp_QGIS_label.png
new file mode 100644
index 00000000..637f5dee
Binary files /dev/null and b/tests/test_data/idgcp_QGIS_label.png differ