From d4009bf283dff6debcd7f59ebf825dfe59d3efca Mon Sep 17 00:00:00 2001
From: Dongdong Tian <seisman.info@gmail.com>
Date: Sat, 8 Aug 2026 21:59:44 +0800
Subject: [PATCH] grdview: Fix the bug when -N is set but level is not
 specified

---
 src/grdview.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/grdview.c b/src/grdview.c
index 6aa25b177df..fe4ce14f870 100644
--- a/src/grdview.c
+++ b/src/grdview.c
@@ -991,8 +991,8 @@ EXTERN_MSC int GMT_grdview(void *V_API, int mode, void *args) {
 	if (GMT->common.R.wesn[ZLO] == 0.0 && GMT->common.R.wesn[ZHI] == 0.0) {
 		GMT->common.R.wesn[ZLO] = Topo->header->z_min;
 		GMT->common.R.wesn[ZHI] = Topo->header->z_max;
-		if (Ctrl->N.active && Ctrl->N.level < GMT->common.R.wesn[ZLO]) GMT->common.R.wesn[ZLO] = Ctrl->N.level;
-		if (Ctrl->N.active && Ctrl->N.level > GMT->common.R.wesn[ZHI]) GMT->common.R.wesn[ZHI] = Ctrl->N.level;
+		if (Ctrl->N.active && !Ctrl->N.implicit && Ctrl->N.level < GMT->common.R.wesn[ZLO]) GMT->common.R.wesn[ZLO] = Ctrl->N.level;
+		if (Ctrl->N.active && !Ctrl->N.implicit && Ctrl->N.level > GMT->common.R.wesn[ZHI]) GMT->common.R.wesn[ZHI] = Ctrl->N.level;
 	}
 
 	if (gmt_map_setup (GMT, GMT->common.R.wesn)) Return (GMT_PROJECTION_ERROR);